07:57 Good morning and welcome to AUTOSPORT Live's coverage of day one of this winter's third pre-season Formula 1 test at Barcelona's Catalunya circuit.

07:58 This test could be the teams' first chance to try Pirelli's wets. The track is currently still damp after Thursday's heavy rain.

07:59 Doesn't look like there's more rain imminent, though. Conditions are currently dry with hazy sunshine.

08:00 Green lights and the test gets underway, with Toro Rosso first out.

08:00 Home driver Jaime Alguersuari is at the wheel for STR today.

08:01 The Spaniard currently has the track to himself, as the damp conditions seem to be dissuading the rest from even going for installation laps for now.

08:01 Jerome D'Ambrosio comes out next in the Virgin.

08:02 Alguersuari is running intermediates on the Toro Rosso.

08:03 Narain Karthikeyan and Heikki Kovalainen set off.

08:03 Hispania is the last team still running a 2010 car, with its new machine set to appear at the final test - wherever that happens to be.

08:04 D'Ambrosio is on full wets.

08:05 Fernando Alonso and Kamui Kobayashi leave the pits in the Ferrari and Sauber.

08:06 Alonso comes down the main straight at half-speed with a reasonable amount of spray being kicked up by the Ferrari.

08:06 Rubens Barrichello brings the Williams out.

08:07 As usual, everyone is doing quick installation laps then pitting, so it's just Alonso and Barrichello on the track now.

08:07 Alonso brings the Ferrari in after his installation run.

08:09 Barrichello is back in the pits, so the track is now empty for the time being.

08:14 After a few quiet minutes, Nick Heidfeld leaves the pits for Renault.

08:14 The German now knows that this seat is his until Robert Kubica is fit to return, Heidfeld having made a good impression in his try-out for Renault at Jerez last weekend.

08:16 As Heidfeld completes his installation run, Kobayashi brings the Sauber back out.

08:20 Kobayashi sets our first time of the morning, a 1m51.803s.

08:21 Which is as tentative as you would expect on a damp track on a completely new tyre design.

08:22 Kobayashi gets down to 1m49.781s.

08:22 Still just the Sauber on the track.

08:23 Karthikeyan is coming out too in the Hispania.

08:24 In news away from the test, Mercedes has announced that Bob Bell - former Renault technical director and briefly the team's chief during the post-race-fixing fall-out - will become Mercedes GP technical director from April.

Bell to join Mercedes GP

08:24 Karthikeyan looks like he's going for a time, while D'Ambrosio is coming out again.

08:25 Meanwhile Kobayashi has improved to 1m47.986s.

08:26 D'Ambrosio came straight back into the pits.

08:26 Kobayashi improves to 1m46.833s as Karthikeyan starts his day with a 1m52.919s.

08:26 Still to appear: McLaren, Red Bull and Mercedes.

08:27 Kobayashi ends that run and pits, he's now done seven laps this morning.

08:28 Heidfeld comes back out for Renault.

08:29 A slight improvement from Karthikeyan, who does a 1m52.242s.

08:30 Alonso comes out for another look at the damp track.

08:31 Heidfeld's first time of the day, a 1m53.990s.

08:32 Kovalainen is also leaving the pits in the Lotus, while Alonso does a constant-speed aero test down the main straight.

08:32 The track is definitely drying quickly.

08:33 It's mainly the pitlane and start/finish straight in the shade of the grandstand that still seems pretty damp.

08:33 Alonso does another constant-speed run.

08:34 The Ferrari is carrying a sensor pole on its roll hoop as the team gathers data. Ferrari has said its plan for later is tyre testing and set-up work.

08:34 Karthikeyan brings the Hispania into the pits.

08:35 Alonso has set his first 'flying' lap, though the 1m57.172s includes long periods running at reduced speed to gather aero data.

08:35 Kovalainen starts what should be his first flying lap of the day.

08:35 He goes straight to second with a 1m48.413s.

08:37 After doing a 1m53.990s best, Heidfeld has returned to the pits.

08:37 Alonso drones past on another constant-speed straight test. Barrichello has come out and is now catching up with the cruising Ferrari.

08:38 D'Ambrosio is back out, while Jenson Button has given McLaren its first installation lap of the day and Sebastian Vettel is leaving the pits for Red Bull now.

08:38 Just Mercedes and Michael Schumacher yet to take to the circuit this morning.

08:39 If you've got any questions for our testing team, you can email us at live@autosport.com.

08:39 Kovalainen improves his best time to 1m47.258s.

08:39 D'Ambrosio returns to the Virgin pits without setting a time.

08:40 Barrichello's first flying lap of the day is the quickest yet, a 1m44.769s.

08:40 Vettel completes his installation lap and a mechanic immediately runs over to cover the rear wing.

08:41 Kovalainen has gone a little quicker: 1m47.193s now his best.

08:41 Barrichello takes the benchmark time to 1m43.551s.

08:42 All of Alonso's laps so far have featured some deliberately slow running for data gathering, so he's still on a 1m56.310s best.

08:42 Vettel's RB7 is wheeled into the garage and the screens immediately go back over the doors.

08:43 Kovalainen takes second from Kobayashi with a 1m46.445s.

08:43 Barrichello goes another 0.4s quicker with a 1m43.148s.

08:44 Alonso is back in the Ferrari pits, having done eight laps so far.

08:45 Kovalainen also comes back in.

08:45 Barrichello keeps going slightly quicker, now on 1m43.020s.

08:47 Heidfeld and Alguersuari go up to second and third, lapping in 1m44.324s and 1m45.737s respectively.

08:47 That was Alguersuari's first flying lap of the morning.

08:48 If you're just joining us, the slow times are because we have a damp track at Catalunya, though the moisture is from yesterday's heavy rain - it's actually becoming sunny at the moment.

08:49 Three cars currently on the track: Heidfeld, Alguersuari and Kobayashi.

08:49 Heidfeld comes in, while Alguersuari improves to 1m44.622s but stays third.

08:49 Kobayashi improves to 1m46.500s and fifth.

08:50 Alguersuari gets up to second with a 1m43.951s, 0.9s down on current pacesetter Barrichello.

08:50 Heidfeld is coming out again too.

08:51 But the Renault returns to the pits after a single lap.

08:51 So Kobayashi and Alguersuari have the circuit to themselves again.

08:52 Alguersuari gets down to a 1m43.583s.

08:52 Dan Batten has asked for a bit of context to start the day: What are typical laptimes from previous years, so as to gauge today's times?

AUTOSPORT.com features editor @TeamAnglais says:

Rubens Barrichello did the fastest time at Jerez last week, a 1m19.832s, compared to Jenson Button's quickest lap of the 2010 Jerez test, a 1m18.871s.

The quickest time of last year's Barcelona test was set by Lewis Hamilton on the final day, a 1m20.472s. At the 2010 Spanish GP, the pole position time was 1m19.995s, the race fastest lap was 1m24.357s and the leaders' pace in the first few laps was in the 1m27s.

With no rubber down yet and parts of the circuit still damp from last night's rain, expect it to be a while before the times get down towards the low 1m20s.

08:53 Kobayashi is back in the pits, so it's just Alguersuari doing laps.

08:54 Alguersuari goes fastest with a 1m42.031s. That's the quickest of the morning by a full second.

08:56 D'Ambrosio comes back out. He's done three installation laps in the Virgin so far but is yet to set a time.

08:56 D'Ambrosio is running right up behind Alguersuari.

08:57 Proving that the track is still damp, Alguersuari gets a big wobble as he gets on the gas on the kerb exiting the final corner.

08:59 The air temperature at the moment is 6.9 degrees, with 13.9 degrees on track.

08:59 D'Ambrosio sets a 1m51.993s, but is doing aero tests so has backed off.

08:59 Kovalainen is coming out for Lotus.

09:01 An hour in, Alguersuari is fastest on a 1m42.031s on the damp track, a second ahead of Barrichello and 2.2s ahead of Heidfeld.

09:01 Kobayashi has the highest lap count with 14. Everyone has set a time except Button, Vettel and Schumacher, though only the latter hasn't left the pits at all yet.

09:01 Alguersuari improves to a 1m41.698s best.

09:03 Kovalainen takes fourth place from Kobayashi with a 1m45.792s.

09:03 D'Ambrosio has been steadily improving and is now onto 1m49.365s in sixth place.

09:05 Button comes out on intermediates, but does just one lap and returns to the pits without setting a time.

09:05 A slight improvement from D'Ambrosio, who does a 1m49.0s.

09:05 Pacesetter Alguersuari is still out, lapping in low 1m42s.

09:07 Kobayashi goes back to fourth, lapping in 1m44.337s.

09:07 D'Ambrosio is controlling some major oversteer out of the damp final corner.

09:07 Alonso comes out of the Ferrari pit.

09:09 The Ferrari resumes its earlier constant speed aero testing, cruising at a steady speed down the straight.

09:09 Kobayashi has improved his time, the Sauber going up to third on 1m43.519s.

09:10 Also still out: Alguersuari, Kovalainen and D'Ambrosio.

09:11 Alonso comes past again at little more than pitlane speed.

09:12 Alguersuari is catching Alonso as he works on aero data-gathering.

09:14 There's still proper water coming up off the main straight. It's in the shadow of the stand and it's still pretty cold, so times aren't going to get quick any time soon.

09:14 Alguersuari goes fastest again with a 1m40.923s, which puts him two seconds clear of everyone else.

09:15 Alonso moves off-line on the straight to continue his aero test and kicks up plenty of spray.

09:15 Karthikeyan has improved the Hispania's pace to 1m48.746s.

09:16 Vettel has stepped up of his Red Bull for the moment as the mechanics work on the RB7.

09:16 Karthikeyan is rapidly catching Alonso now.

09:16 Another new benchmark from Alguersuari, who goes 2.6s ahead of the rest with a 1m40.408s.

09:17 Alonso has picked up his pace slightly with a 1m47.198s.

09:18 Alguersuari pits, spending some time looking for the right gear to trundle down the pitlane.

09:19 The Toro Rosso managed a lengthy 18-lap run, averaging 1m42.688s.

09:19 No one other than Alguersuari has gone below 1m43s yet.

09:19 Alonso ends his run and comes into the Ferrari garage.

09:20 Looks like we'll see a new face in a new place tomorrow...

Liuzzi to test for Hispania

09:20 That might not raise quite as much excitement as Heidfeld's Renault audition, but the HRT seat is the only vacancy left in the 2011 line-up and Tonio Liuzzi has a point to prove after losing his Force India drive.

09:21 Only two cars out now: Karthikeyan and Button.

09:21 Heidfeld comes out too.

09:21 Looks like Button is going to do McLaren's first flying lap of the day.

09:22 Button goes to fourth with a 1m43.580s.

09:23 Button gets down to 1m43.289s and up to third.

09:25 Another improvement from Button, who does a 1m42.000s and takes second, though still 1.6s behind Alguersuari.

09:26 Karthikeyan has gone quicker than before too, doing 1m46.742s.

09:28 Heidfeld is the latest driver to wobble his way out of the still-wet final corner.

09:30 The surface is slowly drying, but there is still lingering dampness.

09:30 Humidity was 90% at the start of the session but is now 74% and falling.

09:30 Button and Heidfeld pit, now it's just Kovalainen on the circuit.

09:32 Vettel is coming out for Red Bull.

09:33 Kovalainen jumps to third place with a 1m42.051s.

09:34 Vettel comes back in straight away - he didn't push on that lap and seemed to be just getting a feel for the track conditions.

09:35 Away from the test, the big question facing F1 at the moment is whether the season-opener in Bahrain should go ahead.

Roger Wise asks: Should the first GP of the season not take place as intended, would there be an alternative venue, or would there be extra testing somewhere to compensate?

AUTOSPORT.com managing editor @eligp replies: As things stand now, it is very likely that the test there will be cancelled, because it seems too risky to travel to Bahrain at the moment.

The race is a bit further away, but teams don't have a lot of time before they have to ship everything to Bahrain, so a decision will have to be made quickly, meaning the tension would have to ease very fast for the race to go ahead as scheduled. Ecclestone said the decision will come next week.

Some teams have already said that it would be very hard for them to travel to another place for the race, because a lot of their equipment left for Bahrain some time ago, so it seems to me that the most likely possibility is that the race is postponed, because there is a lot of money involved for the event to be just called off.

The question is when would the race take place, considering that the season ends in November... Ecclesstone has already joked about a Christmas GP.

09:35 Kovalainen improves to second place with a 1m41.115s.

09:36 As Vettel came in a few moments ago, a Red Bull mechanic once again sprinted over to hide the secrets of the rear of the RB7.

09:38 Kovalainen has now pitted, so it's just Heidfeld's Renault on the circuit.

09:38 Karthikeyan comes back out.

09:39 Hispania is using its 2010 car here still, but for the last time, with the new model due to make its debut at the last test of the winter. Although it has released images of the F111, it is not ready to run yet.

09:39 Very little spray from Heidfeld's Renault as he blasts down the main straight.

09:39 Kobayashi comes out in the Sauber.

09:40 The spray is still in the area in the shade of the main grandstand, where we are, and that is proving slowest to dry.

09:40 Kobayashi just had a moment at Turn 10, he took to the run-off but is back up to full speed now.

09:41 It was quiet earlier, but now there are quite a lot of fans filtering into the circuit.

09:41 Days when Alonso is running tend to see a good turnout for the Spanish tests, though more so at weekends.

09:42 The part of the main grandstand that is opposite the Ferrari garage is getting particularly full.

09:42 Karthikeyan does his best time so far for Hispania with a 1m43.575s.

09:43 Alguersuari sets off again for Toro Rosso. He's still fastest by 0.7s over new second-place man Kovalainen.

09:47 Heidfeld pits and the Renault crew do a practice pitstop.

09:48 Early pacesetter Barrichello is back on the circuit. He's been pushed back to fourth in the Williams.

09:49 Pitstop practice continues for Renault as Heidfeld does another out/in-lap.

09:52 There are only two cars on the circuit now, Button and Barrichello. They're about half a lap apart.

09:53 We haven't seen anything of Mercedes yet today, but will do very soon... @OfficialMGP: "Michael's in the car and ready to head out to get our programme underway as it starts to warm up in Barcelona..."

09:53 Barrichello goes back to the top of the times with a 1m39.162s. That's 1.2s quicker than Alguersuari.

09:53 But within moments, Button deposes Barrichello with a 1m38.429s.

09:53 The track is definitely improving now.

09:55 Barrichello goes a little quicker than before with a 1m39.129s.

09:55 The Red Bull fires up again as Vettel prepares to head out.

09:58 Temperatures are creeping up: now 9.6 degrees air, 18.3 track and 70% humidity.

09:58 Button backed right off after that quick lap that put him fastest, though he's still out. Barrichello, Kobayashi and Vettel are also on the circuit.

09:59 Schumacher has now done his installation lap but hasn't gone for a time. Last car to emerge today will be Paul di Resta's Force India.

09:59 Vettel and Button come back in, so Red Bull still yet to go for a time today.

10:03 Unlike Jerez and Valencia, Barcelona operates an official lunchbreak in testing, so we're now halfway through the morning session.

10:04 Barrichello and D'Ambrosio are currently the only men on track, and we're still about 15s off what we'd expect for dry times.

10:04 D'Ambrosio comes in as Karthikeyan rejoins.

10:08 The track was briefly empty as Barrichello finished a nine-lap run averaging 1m41.0s.

10:08 But now Alguersuari rolls straight out for another blast.

10:09 Karthikeyan only did one flying lap, but it was his best yet - a 1m41.152s, which puts him fifth.

10:09 After cruising down the pitlane, Karthikeyan went straight onto the circuit again.

10:09 Schumacher is back out and looks like he'll be doing his first flying lap of the morning.

10:10 Alguersuari didn't do a flying lap, he comes straight back in.

10:11 Schumacher's first flying lap is the quickest of the day, he goes top with a 1m37.466s.

10:13 That was a quick run, he now pits again.

10:14 There's now a proper dry line emerging at the exit of the final corner.

10:14 Vettel's Red Bull goes back out.

10:14 There's a large crowd gathering outside the Ferrari motorhome, we suspect that means Alonso is inside.

Or they just think he is...

10:16 Vettel starts what should be his first flying lap of the day. Will he go straight to the top as Schumacher just did?

10:16 Kobayashi is also back out in the Sauber, joining Vettel and Karthikeyan.

10:18 A more cautious start from Vettel, who does a 1m39.959s.

10:18 That puts the Red Bull fourth.

10:19 Now Kobayashi goes fastest with a 1m36.264s, 1.2s quicker than Schumacher's previous benchmark.

10:21 Vettel pits and the Red Bull mechanics throw a corner over the car's rear straight away. He's wheeled into the garage and boards go straight across the front to deny any prying eyes. All particularly secretive.

10:22 That just leaves pacesetter Kobayashi on the circuit now.

10:23 Lotus news from @MikeGascoyne: "Track starting to dry and times falling. Currently stopped fixing a small water leak, ready to go soon"

10:24 From our vantage point in the commentary area, it's hard to see which tyres drivers are using, with the shallow grooves of the intermediates looking like slicks from a distance and no tyre markings in operation yet. @H_Kovalainen has said he's been on intermediates at least.

10:28 Kobayashi has pitted, so the track is empty.

10:28 Four flying laps from Kobayashi on that run, averaging 1m39.2s, though times won't mean much until the track is properly dry.

10:29 Big crowd in the pitlane outside Williams. Think it's team guests rather than the world's media believing Barrichello's fastest time at Jerez means he's going to win the championship.

10:30 There's music booming out of the main grandstand to stop the early fans getting any peace and quiet while the cars are all in the pits.

10:30 While it's quiet, remember that you can email questions to us via live@autosport.com.

10:30 Looking at the Sauber in the pits, Kobayashi has definitely on intermediates for the time-topping run.

10:31 The track is rapidly getting too dry for inters, though.

10:32 Teams may now be waiting until after lunch for some proper dry-tyre runs.

10:32 Though with the Pirelli inters new to everyone, they may want to see how they perform on an increasingly dry track.

10:34 Karthikeyan breaks the on-track silence by heading out for Hispania, and more engines are firing up elsewhere in the pitlane.

10:34 Kobayashi is going back out too.

10:36 Here is Renault's schedule for the day, from @OfficialLRGP: "Pit stop practice complete for Nick. Vitaly is just about to start his. Then, Vitaly will remain in the car for the rest of the day."

10:37 Kobayashi didn't go for a flying lap on that occasion.

10:39 Though it feels early for Renault to be switching drivers, this is technically Petrov's day in the car. Heidfeld was doing some pitstop practice this morning (and completed 27 laps along the way) and will be back in for Saturday and Monday. Petrov is doing the rest of today and Sunday.

10:41 Alonso is leaving the Ferrari pit. Most of his 15 laps first thing this morning involved constant-speed aero testing, so he has yet to really attack.

10:42 The track's getting a little busier, with Ferrari, Williams, Hispania and Virgin now all out.

10:43 AUTOSPORT.com's @gcreighton brings news of Alonso excitement: "Just seen Alonso mania in action, with a crowd of paddock guests running across the roof of the pit building to catch a glimpse of him."

10:43 Vettel is coming out too. Temperatures aren't rising very quickly here still, only up to 11 degrees air, 20 degrees on track, though humidity has dropped to 58%.

10:44 D'Ambrosio goes second for Virgin with a 1m36.411s.

10:45 He's within a tenth of Kobayashi's fastest time, and 3.5s quicker than champion team Red Bull. Though Virgin is clearly making good progress, we'll put this one down toa drying track.

10:46 More evidence of conditions improving as Barrichello does a 1m34.067s to go fastest by a massive 2.197s.

10:46 D'Ambrosio right on Barrichello's pace - he laps within 0.365s of the Williams and retains second.

10:47 Vettel goes up to fourth on a 1m37.172s.

10:47 Button just slowed coming onto the pits straight, then gave the McLaren a big boot-full of throttle, possibly trying to warm the tyres.

10:47 We're squinting as hard as we can from the commentary box windows to see what tyres people are on...

10:47 Barrichello blasts to a 1m31.334s, 3s clear of the rest.

10:49 Alonso goes up to fourth with a 1m36.978s.

10:49 Faster still from Barrichello, onto 1m30.421s.

10:50 We're going for an educated guess that he's doing these times on slick tyres now.

10:50 The track definitely looks ready for slicks and the massive jump in pace on this run suggests he's made the move from intermediates.

10:50 Everyone else has come back in except D'Ambrosio, who's lapping in 1m35s.

10:51 Barrichello does a 1m31.2s next time past.

10:51 A sea of red overalls disappears behind big white boards outside the Ferrari pits as Alonso is pushed into their haven.

The leading teams are noticeably more secretive here than they were at Jerez or Valencia. Suggests new parts are appearing on the cars.

10:52 A question from live@autosport.com...

Charles Wenz asks: No mention yet of Paul di Resta, is the Force India broken again?

The car hasn't been out yet, but we've not heard anything from the team as to whether they have a problem or are just waiting for track conditions to improve.

We know they follow our live commentary, so perhaps they'll offer an update...

10:52 Barrichello raises the bar again with a 1m30.045s to go 4.3s clear of the pack.

10:53 There are just a few damp spots in the shade of the main grandstand now, the rest of the track is dry on the racing line.

10:55 Nicholas Mitchinson asks: What are the other track options if the Bahrain test is cancelled? Do you think they could head to the Portimao circuit in Portugal?

AUTOSPORT.com features editor @TeamAnglais says:

It's one of several possibilities, if the Bahrain test is cancelled and the teams decide they want to replace it. Paddock rumours today seem to suggest that staying at, or coming back to, Barcelona for another test is the most likely option.

Or, because the cars need to head in the direction of the Middle East soon for the Bahrain race (assuming it happens), Abu Dhabi has also been mooted as a potential venue. Nothing is decided yet though. FOTA is having a meeting about it today, so let's see what comes of that.

10:55 Keep your questions coming to live@autosport.com.

10:56 D'Ambrosio does a minor improvement and gets to 1m34.175s, 4.1s off Barrichello.

10:56 We reckon the Virgin is on slicks too by the look of it.

10:58 Another slightly quicker lap from the Belgian rookie, who does a 1m34.129s. Alguersuari is coming back out for Toro Rosso, and Barrichello is still out and lapping in high 1m30s.

10:59 Alguersuari is definitely on slicks and gives us our first sub-1m30s time of the day, going fastest on 1m29.957s.

10:59 Barrichello has come back in, as D'Ambrosio finds a little more speed with a 1m34.035s.

11:00 Alguersuari goes faster again with a 1m29.197s.

11:01 Being in the commentary boxes is great for a panoramic view, less good for picking out tyre tread, as AUTOSPORT.com's @gcreighton is finding out: "Definitely should have packed some binoculars to help pick out the details from way up here in the commentary boxes."

11:01 Kovalainen is out on slicks, as we expect most people will be now.

11:04 Button leaps to the head of the order with a 1m27.094s.

11:05 A flurry of improvements now as everyone gets up to speed on slicks. Kovalainen, Karthikeyan and D'Ambrosio lap in 32.4, 33.7 and 33.9 respectively to go fourth, fifth and sixth.

11:05 Even in testing Button is rather good in changeable conditions: he does a 1m26.365s now.

11:05 That puts the McLaren 2.8s ahead of second-placed Alguersuari.

11:07 Kovalainen and Karthikeyan improve by a few more tenths each.

11:08 Alonso is coming back out as Button pits. Kovalainen and Karthikeyan are the other men still on the circuit.

11:09 Alonso comes down the pits straight at full speed, which is an unusual sight after his morning of aero tests.

11:10 Alonso goes fastest - a 1m25.597s puts the Ferrari 0.8s clear of Button.

11:12 Vettel just did a single lap and is heading back towards the mechanics, who are donning their KERS safety gloves in preparation for his arrival.

11:13 Alonso is now the only man on the track, which will do fine for his fans in the grandstand.

11:13 Barrichello comes out to join the Ferrari.

11:14 Barrichello was catching Alonso on track but backs off through the final chicane to find some space.

11:16 Alonso improves his time slightly with a 1m25.485s as he remains fastest.

11:19 Barrichello improves a little with a 1m29.197s. Karthikeyan and Alguersuari are also out.

11:20 Alonso comes in to end his session-topping run.

11:20 Alguersuari has gone faster too with a 1m27.267s.

11:22 Another improvement from Alguersuari, a 1m26.756s brings him closer to second-placed Button.

11:22 Schumacher is back out. He's yet to do a time since the track has dried.

11:23 A quick answer for the concerned McLaren fan who has emailed live@autosport.com three times this morning worried about the situation there. Be calm. Button has run through a few short stints, he's done 22 laps and is second on the timesheet. Everything is fine.

11:24 Schumacher's first dry-ish time takes him up to fourth on a 1m28.306s. He's had a very quiet morning, with only six laps so far.

11:25 Vettel puts in his first slick time today too, taking fourth from Schumacher with a 1m27.175s.

11:26 Vettel's pit board says 'L4' so expect a few more laps.

11:27 Vettel improves to 1m26.640s and third place.

11:31 Vettel is due in now, and sure enough he comes down the pitlane.

11:31 Button, Alguersuari and D'Ambrosio are the drivers currently on the circuit.

11:34 D'Ambrosio caught up with Button and was tailing the McLaren for a spell, but now pits.

11:34 Alguersuari goes up to second place with a 1m26.193s, 0.708s behind Alonso.

11:36 We can't quite tell if that Spanish 1-2 has been greeted with a burst of enthusiasm from the crowd because there's very loud music booming out of the grandstand and drowning everyone out again.

11:36 Alonso is on the track again now, as Alguersuari continues to lap in mid-1m26s.

11:37 Kovalainen comes out again in the Lotus.

11:37 Alguersuari edges closer to Alonso with a 1m26.117s, putting him 0.6s behind.

11:39 There are still a good few people gathered in the grandstand opposite the Ferrari garage, though it is likely to be busier tomorrow.

11:40 This is the busiest day yet for the live@autosport.com question inbox, so we won't be able to answer everyone's queries, but we'll get through as many as we can - and do keep them coming.

11:41 Here's one from Mihai Pais, who asks: Is there any way of telling if the teams quickest laps were made with low fuel and soft tyres?

AUTOSPORT.com features editor @TeamAnglais says:

There's no way to know for sure, unless the team or driver tells us afterwards.

We can track how many laps each stint was and on which lap of it the fastest time was set, so we know the minimum fuel each car must have been carrying. But there's no way for us to know how much extra was on board.

As for the tyres, Pirelli won't begin marking the different compounds until the first race but we can watch the drop-off of laptimes over the course of a stint and make an educated guess. The super soft tyre, for example, loses around 1.5s after just one lap, so that's quite easy to spot. It's not so easy to read into the others, so it's always an educated guess at best.

11:41 Alguersuari has come back in - and there wasn't anything like the urgency to cover up the STR as there was at sister team Red Bull when Vettel last pitted.

11:43 Vettel is now coming back out again.

11:44 Kovalainen improves his time a little with a 1m30.667s.

11:45 The sun is slowly moving around to eliminate the shade on the pit straight and with it the last remaining damp patches.

11:46 Barrichello is back out, and improves to a 1m27.447s.

11:46 Temperatures are creeping up still as well, 13 degrees air and 25 track now.

11:47 The lunchbreak is scheduled to start in just under a quarter of an hour. At this rate, the track should be totally dry when running resumes for the afternoon and teams can get on with some serious work.

11:47 Red Bull pit board says seven more laps for Vettel on this run.

11:49 The session has been stopped.

11:50 Looks like Barrichello's Williams has caused this red flag.

11:50 It was just Barrichello and Alguersuari in action at that point, and the Toro Rosso is back in the pits.

11:50 We can't see the first half of the track from our vantage point, and we reckon that's where the Williams has come to a halt.

11:51 Timing screen reports that Barrichello has parked at Turn 7, and that the track is clean, so no fluid spilt.

11:55 It's possible that the track officials will decide to go straight into the lunchbreak now rather than trying to restart for just a few minutes. We can't quite see through the trees if the Williams has been loaded onto the truck yet.

11:56 The Williams is now on its way back to the pits on the truck, covered by a sheet as is standard practice in testing.

11:59 From the outline under the sheet, the Williams seems intact, so looks like a mechanical problem.

11:59 News from Renault via @OfficialLRGP: "A few issues have kept Vitaly in the garage this morning. He'll be back out after the lunch break at 14:00."

12:00 The lunchbreak is starting now, so the session will resume at 2pm local time.

12:00 We're off to take a break as well, but we'll return to bring you full live coverage of the final three hours when cars return to the track after lunch.

12:58 The session is about to resume on a bright, sunny day here at the Circuit de Catalunya.

12:59 The sunshine has finally made it all the way across the main straight, drying up the last remaining dampness from yesterday's heavy rain.

13:00 We're back under green, but there's no immediate rush out of the pitlane.

13:02 While we are waiting, let's take a look in the AUTOSPORT Live inbox ...

13:03 Guhan Subramaniam asks: Everyone knows the Red Bull is clearly faster then any other car by at least five tenths, so why are they always sandbagging? I do not believe it will try to make other teams think it has no pace.

AUTOSPORT.com features editor @TeamAnglais says:

"It is true that everywhere we try read between the lines, the Red Bull seems to be the fastest car. It's consistency over long stints and ability to make tyres last longer than we expect stands out. It's exit speed out of fast corners at Jerez was quicker than all the others, even when it was lapping slower. And the rear wing flap was opening earlier and for longer than all the others, suggesting a comparative surplus of downforce. But because of the nature of testing, that's all still guess work for us.

"The team isn't sandbagging, as such. As veteran F1 engineer Frank Dernie explained to us when he got in touch with Live at Jerez, it's far less vital for a team to spend time testing on qualifying fuel. So Red Bull is likely just focused on heavy fuel race pace, rather than trying to hide its performance from the likes of Ferrari and McLaren.

"We won't know for sure how quick the RB7 is until the first race, but you can be sure that the rival teams know more about each others' performance than we do."

13:04 Meanwhile, Alonso has broken the silence and is on track in his Ferrari.

13:04 It's just a single lap for the Spaniard and he trundles back into the pitlane.

13:05 Kovalainen screams past to begin a run in his Lotus, as does Karthikeyan in the HRT.

13:06 Alonso set the pace this morning with a 1m25.485s lap in the hour before lunch when the track was at its driest.

13:07 Times should improve further this afternoon with the circuit now fully dry and rubber beginning to go down on the racing line.

13:08 Kovalainen and Karthikeyan set their best times of the day so far, with those two having the track to themselves at the moment.

13:09 Alonso has been in and out of the pits several times and is making a practice start at the end of the pitlane each time he dives in.

13:11 Alonso is just ahead of Kovalainen on the circuit and lets the Lotus through heading in to the final complex.

13:12 1m27.512s is Schumacher's best of the day so far as he makes a proper start on lapping in the Mercedes. The German avoided much of the damp running this morning and has only completed 12 laps so far.

13:14 Car coming into the pits again - and no surprise to see it is Alonso heading down for another practice start.

13:16 Schumacher wraps up his three-lap outing and heads to the Mercedes garage.

13:17 Alonso is also back in the pits and this time the Ferrari is wheeled back into the garage.

13:19 Kovalainen pits his Lotus and the track falls silent.

13:22 Robert Haggerty asks: With the talk of Red Bull and Ferrari putting up screens to hide their new developments, was there not a rule
introduced a few years ago where teams were forbidden from using such practices?

AUTOSPORT.com features editor @TeamAnglais says:
"Good question. There was, but that rule only prevents them from doing it during grand prix weekends. They're free to hide as much as they can during tests."

13:23 Kobayashi has emerged from the pits in his Sauber.

13:27 Kobayashi clocks an improvement to 1m27.470s for sixth fastest. He's since been joined on track by Karthikeyan in the HRT.

13:27 The session has been stopped.

13:28 Karthikeyan heads into the pits, so it seems to be Kobayashi stopped in the first sector of the lap.

13:30 The Sauber has come to a halt on the track at Turn 5.

13:31 No oil reported down on the circuit and the recovery truck is working to pick up Kobayashi's car and bring it back to the pits.

13:32 It looks like he was testing the limits of the Sauber's fuel tank - something the teams all try to do at some point during the tests.

13:36 Prolific emailer David Surgenor asks: Is there any expectation as to
what the hyped Mercedes big upgrade package will be in Bahrain?
Mechanical/aero/thee-element front wing?

AUTOSPORT.com's @TeamAnglais says: "Our technical correspondent Gary Anderson spotted that the Mercedes ran with slots cut into the front wing at Jerez, and he suspects it is in preparation for a move away from the two-element front wing.

"You can read his full analysis of the subject, including the
difficulties the team will face in making it work, in this week's
AUTOSPORT magazine."

Available as a Digital Edition here

13:37 The truck carrying Kobayashi's Sauber makes its way around Turn 10 and into the final part of the lap, so the session should resume shortly

13:39 The track is open again.

13:40 The green flag came out surprisingly early there, with Alguersuari almost having to dodge the flatbed truck in the pitlane.

13:41 Schumacher, Alguersuari and Alonso are back out and on to flying laps.

13:44 There isn't a cloud in the sky here - ideal conditions for some dry running after this morning's work testing intermediates on the drying track.

13:44 Karthikeyan clocks his best lap of the day in the HRT.

13:46 Alonso is now three laps into a run with his pace around 1m27s at the moment.

13:47 News via AUTOSPORT's @eddstrawF1 that Sauber has had a problem with its KERS this morning and is running this afternoon without the device active.

13:49 But that was nothing to do with Kobayashi's recent halt, which as we reported was a test of how the Sauber reacts when its tank gets empty.

13:51 No recent improvements in the headline times ... and the red flag is out again.

13:52 It looks like Alguersuari hasn't made it back around to the pits in his Toro Rosso.

13:53 The timing screen tells us he's in the gravel at Turn 4.

13:53 The recovery truck is heading off in that direction.

13:55 Despite our excellent view of the circuit from high above the main grandstand, we can't see over to the first few corners.

13:56 The track temperature is up to 28 degrees in the warm afternoon sunshine.

14:01 Williams mechanics are busy - news via @WilliamsF1Team: "Possible engine issue for Rubens, team changing it while investigating"

14:02 Alguersuari's Toro Rosso is back in the pits on the back of a truck.

14:03 There's no sign of damage, but dusty wheels does confirm the Spaniard has been in the gravel.

14:04 With that all tidied up, the session is back underway.

14:05 D'Ambrosio is the first to head out in his Virgin MVR-02.

14:06 Karthikeyan has joined him on track, but they are the only two circulating for the moment.

14:08 Mark Ward asks: With the Bahrain test looking less and less likely to happen, this could be the last test before the we actually get some racing. Do you think the teams will have altered their plans for Barcelona just in case? I would imagine those who only brought new cars to Jerez maybe particularly concerned.

AUTOSPORT.com features editor @TeamAnglais says: "We don't know yet that the Bahrain test won't go ahead. If it doesn't, the teams seem to be trying to arrange a replacement venue. So they'd still have the same number of test days before the first race."

14:10 Karthikeyan moves up a place on the timesheets from ninth to eighth with a lap of 1m28.393s.

14:12 Paul Di Resta has finally been out for a lap in his Force India. We're not quite sure why, but that was his first outing of the day.

14:14 Alonso's recent attempts to put in a long run have been disrupted by the red flags but he's now out and has resumed lapping in the late 1m27s bracket.

14:15 Karthikeyan wraps up a five-lap outing and heads back to the HRT pit.

14:18 D'Ambrosio is circulating in his Virgin as well, but his times are some way off the pace, around 1m35s.

14:22 Alonso pits to wrap up his run, with the times fading to 1m29.484s the last time by as he got to the end of the life of his Pirellis.

14:24 Kobayashi clocks his best time of the day with a 1m27.470s. He's sixth fastest overall.

14:25 It's been a while since we've seen the McLaren - before lunch in fact. However, Button is now on track in the MP4-26.

14:29 Not a lot of action from the Red Bull lately either. The RB7 is up on stands at the moment, with mechanics working at the rear of the car.

14:30 Meanwhile, Kobayashi is working his way up the order - a 1m27.340s lap puts the Japanese fifth quickest.

14:32 Button is now on the fourth flying lap of his first outing this afternoon.

14:33 Kobayashi has pitted his Sauber, so the only other men circulating are Schumacher and D'Ambrosio.

14:35 A fairly short run to get Button's afternoon underway. He's pushed into the McLaren garage after four timed laps, the best being a 1m28.073s

14:36 Schumacher, Karthikeyan and D'Ambrosio are still pounding around, all three running within a few seconds of eachother on the track.

14:37 The distinctive livery of the Force India flashing by means di Resta is on course for his first timed lap of the day.

14:39 It's a 1m31.665s from di Resta as he finally joins the timesheet in 10th quickest.

14:42 Bit of a race for track position developing as D'Ambrosio in the Virgin chases down Karthikeyan's HRT.

14:43 Di Resta pulls the Force India into the pits after his first run of the day. Schumacher follows him down the pitlane.

14:45 D'Ambrosio is still just about a second behind Karthikeyan on track.

14:47 Now the Belgian is finally through and the Virgin has pulled out a gap of around two seconds as the pair flash past the pits once again.

14:50 Schumacher is now catching that pair as he works on a long run in his Mercedes.

14:52 Button is now back on track in his McLaren, clocking a 1m30.923s on the first timed lap of his run.

14:53 In the battle for track position, Schumacher has now dispatched Karthikeyan's HRT and lines up the Virgin of D'Ambrosio for a move into Turn 1.

14:54 Kobayashi shaves a little more off his best time of the day with a 1m26.666s.

14:55 Karthikeyan wraps up a 12-lap outing, heading back to the HRT garage.

14:58 D'Ambrosio's MVR-02 looks a little nervous out of the final corner, with the Belgian forced to correct its trajectory on several laps as he accelerates on to the long main straight.

14:59 Alonso has kicked off another run and is lapping in the low 1m27s bracket on his fresh rubber.

15:00 Paul di Resta is back underway in his Force India, clocking a 1m28.839s to move up to ninth quickest.

15:05 Still no sign of action at Red Bull. The RB7 hasn't been out for a while, with no laps logged since before the lunch break.

15:06 Renault also has the spanners out, via @OfficalLRGP: "A few issues with the KERS software today. Hopefully Vitaly will get some running before the end of the session."

15:08 Recent improvements in the headline times with di Resta improving to a 1m28.348s for eighth and D'Ambrosio clocking his best at 1m30.950s

15:11 D'Ambrosio lets Alonso through on the road. The Spaniard continues on a long run with his current pace edging out towards 1m28s now.

15:14 Other than the home hero, Schumacher, Karthikeyan and D'Ambrosio are the men lapping with 45 minutes of the session remaining today.

15:17 Karthikeyan is on top of the the milage chart so far today with 96 laps. We've also seen D'Ambrosio Virgin pass below us here 93 times.

15:20 Alonso pits to end a 17-lap long run. His times dropped from initial 1m27s pace towards 1m29s over the final couple of tours.

15:21 Schumacher has been circulating continuously for the last hour in what looks like a race simulation for Mercedes.

15:24 Schumacher is six laps into the third stint of what is so far a 37-lap race, circulating in the low 1m30s bracket.

15:25 Button is back out in the McLaren, while the KERS dramas are now solved at Renault and Vitaly Petrov is out for the first time today.

15:26 There are also signs of activity at Red Bull, with Vettel now in his car and looking set to head out for the final half-hour.

15:26 Petrov joins the timesheet in 12th position with a lap of 1m35.174s before heading back to the Renault garage.

15:27 The screens are parted at Red Bull and Vettel heads out for his first lap of the afternoon.

15:30 Button has kicked off a run in his McLaren, lapping in the 1m29s. His pitboard suggests another six laps are planned.

15:32 Vettel also has six laps to go on this run, which he has kicked off with a lap of 1m26.737s.

15:34 Vettel now clocks his best of the day so far - 1m26.584s. The track has improved a lot since he was last out before lunch.

15:36 Alonso is also on a 1m26s pace at the moment, making his way past D'Ambrosio's Virgin on his latest lap.

15:37 Petrov has chalked up eight laps so far this afternoon, with a lot of visits to the pits for systems checks in the Renault.

15:40 Schumacher heads in for the third pitstop in his race simulation. He did 15 flying laps on that set of Pirellis.

15:41 The Mercedes has been going since 15:22 local time, completing 50 laps of a race distance so far.

15:41 The Mercedes-powered Force India is also moving up the order with di Resta taking fifth quickest in 1m26.575s.

15:42 Alonso is ten laps into his latest run, lapping in the mid 1m27s.

15:44 Alguersuari is about to get underway in his Toro Rosso. The Spaniard has been sidelined since earlier finding his way into the Turn 4 gravel

15:45 It looks like Toro Rosso are carrying out a cooling test in the pitlane, as Alguersuari has been sitting in the car with the engine running.

15:47 Vettel is off out again in his Red Bull.

15:49 It looks like another seven lap run for the world champion as he flashes past the Red Bull man hanging his pitboard over the wall.

15:51 Vettel puts his Red Bull on top of the times for today with a lap of 1m24.374s.

15:52 Plenty of cars circulating in these final few minutes with only Algusuari and Kovalainen in the pits.

15:53 Vettel's next lap after his session topper was a 1m27.532s, but he may have had traffic in the form of D'Ambrosio's Virgin.

15:57 Schumacher continues to circulate in his Mercedes. He's about to clock the 63rd lap of his outing - just short of the race distance here.

15:57 Alguersuari moves up to fourth fastest in the Toro Rosso with a 1m25.698s.

15:58 Barrichello also makes a late improvement with a 1m27.241s in his Williams.

15:59 The man with the chequered flag is readying himself, with just a minute left of the day here.

16:00 Vettel brings his Red Bull into the pits as the flag comes out to end the first day at the Circuit de Catalunya.

16:01 Alguersuari is a late mover in the timesheets, putting the Toro Rosso up to third quickest with a lap of 1m25.638s.

16:02 Schumacher pits after a successful 65-lap race distance in his Mercedes.

16:02 As the final cars trail back into the pits, we are off to hear from the drivers.

16:02 Stick with AUTOSPORT for all the reaction from day one, and we'll be back with live coverage tomorrow from 08:00 GMT.