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As it happened: Friday - Practice
By Pablo Elizalde, Matt Beer, Edd Straw, Glenn Freeman, Ben Anderson and Dan Cross
The live commentary has ended. No further updates will be posted.
07:42 Welcome to AUTOSPORT's live coverage of the Friday free practice action from the Spanish Grand Prix weekend. The countdown to the first running of the European season is on, and it will be fascinating to see how the pecking order looks following the first big upgrades of the season to the cars.

07:47 While it would be a surprise to see Mercedes knocked off of its perch this weekend, Lewis Hamilton and Nico Rosberg believe that the characteristics of the Barcelona circuit will allow their pursuers to close the gap.

Mercedes motorsport boss Toto Wolff has highlighted Ferrari as the Silver Arrows' biggest threat, and there will be a lot of attention on the performance of the Red Bulls, at a circuit that should play to the cornering strengths of the RB10.

07:59 It's a sunny start to the day in Spain, meaning the teams can get all of the track time they need to test their new parts.

08:00 We're underway, with several cars heading straight out. Marcus Ericsson's Caterham is the first.

08:01 Track and air temperature are both 19C at the moment.

08:02 Felipe Nasr is preparing to go out on an installation run. He's in the car instead of Valtteri Bottas this morning.

08:04 As Daniel Ricciardo takes to the track, that leaves Jenson Button as the only driver not to leave the pits for an installation lap yet.

08:04 Daniil Kvyat sets the first time of the session - a 1m37.986s.

08:07 The Russian is the only car on track now, and he comes in with four laps on the board.

08:09 This circuit has several corners that are a big test for the cars. We've got EDD STRAW and BEN ANDERSON trackside in this session, and at the moment they are perched at Turn 3. Anderson describes it as "a great place to see who has downforce and who doesn't".

08:12 Aerodynamics have been at the heart of Ferrari's relatively poor form this season and both Kimi Raikkonen and Fernando Alonso's cars have been sporting flo-viz paint this morning - rear and front wing respectively - as they try to make improvements.

08:13 Systems checks completed and we now have a silent race track.

08:15 The development race doesn't only take place at the front of the grid in F1. Even the teams at the back of the field are constantly chasing performance.

Marussia is running its new parts on Jules Bianchi's car so it can get a back-to-back comparison today with the original-spec on Max Chilton's. The Briton will get the updates from Saturday.

Both cars are also running new front suspension parts aimed at improving aero performance, and away from testing upgrades the team's focus is going to be on tyre wear today - a factor it is expecting to be vital in the race.

08:16 After a few minutes of silence we have cars on track again: Hulkenberg, Magnussen, Bianchi, Perez, van der Garde, Maldonado, Button.

08:18 Pirelli offers a friendly reminder of the new tyre rules that means Friday practice gets under a busier start these days:

"This year as you probably know by now each driver has one set more of the harder tyre, for the first 30 minutes of FP1."

08:19 Button, Bianchi and Maldonado all have times on the board now. The McLaren is fastest on a 1m30.717s.

08:20 Magnussen briefly takes top spot from his team-mate, before Alonso goes fastest for the first time.

08:21 Perez is being battered by his side mirror! He catches it and drives back to the pits one-handed.

08:22 EDD STRAW from trackside: "The Ferrari looks strong on the way into Turn 3. Not quite as convincing at the exit as the rear grip runs out but still not too bad.

"The Lotus looks a bit more stable and predictable here. It's early days but that suggests maybe a step with the balance has been made. It's still not great, but heading in the right direction."

08:22 Rosberg is now fastest, while Hulkenberg and Massa have also gone quicker than Alonso.

08:22 Two overall best sectors from Alonso suggest he is about to go back to the top of the times...

08:23 Alonso does indeed go fastest, but Hamilton is now on a quicker lap. Nasr goes second for Williams, and is then pipped by Button.

08:24 The timing screens are lighting up with personal best sector times as we approach the final five minutes for teams to run their extra set of prime tyres in this session.

Hamilton and Rosberg have both beaten Alonso's time, so we have our first Mercedes 1-2 of the European season.

08:26 Vettel has come to a stop at Turn 5. The reigning champion jumps out and helps the marshals push his car away to safety.

08:28 EDD STRAW tells us: "The Williams is still asking a lot of the rear in Turn 3. Massa has a wobble on the entry followed by a moment at the exit. He runs wide onto the dust and just beyond the limit of the track."

He also reports that the Ferrari's engine note has changed compared to the first four races of the season.

08:30 As most of the cars tour back to the pits with the 30 minute-mark approaching, the top 10 is as follows:

1 Hamilton; 2 Rosberg; 3 Ricciardo; 4 Alonso; 5 Button; 6 Raikkonen; 7 Nasr; 8 Hulkenberg; 9 Massa; 10 Sutil.

Vettel is 15th, with just four laps on the board before his car stopped on track.

08:32 So half an hour in, the main developments so far:

* Hamilton is the fastest in the early running, leading a Mercedes 1-2 with a time of 1m28.028s.
* Vettel stopped on the exit of Turn 5 and it looks like his session could well be over.
* Perez is having his mirror fixed after it came loose.

08:34 More from BEN ANDERSON on what he saw at Turn 3 during those first runs: "Alonso is hustling the Ferrari through here. The Ferrari looks solid but is requiring a few small corrections in the later phase of the corner.

"Unsurprisingly the Red Bull looks smothered in grip. We reckon the ranking in terms of Turn 3 performance is Red Bull, Mercedes, then Ferrari. Lotus also looks decent.

"The others are needing all the track to get through unscathed. A conservative entry appears to be helping the McLaren through the rest of the corner."

08:35 With no cars on track, our 'experts' report that they are being entertained by "giant ants" on top of the tyre wall at Turn 3.

08:37 After supervising his car's recovery, Vettel is heading back to the pits on the back of a scooter.

08:38 On those early runs, Ferrari was running flo-vis paint on the front of Alonso's car, and on the rear of Raikkonen's.

08:39 Lotus breaks the silence on track, sending both Maldonado and Grosjean back out.

08:40 While there is only 0.1s between the two Mercedes drivers at the front, third-placed Ricciardo is 0.7s down on Hamilton as best of the rest.

08:43 Maldonado replaces Ricciardo behind the Mercedes in third, but still 0.7s off the pace.

08:47 Vergne (who improves to P9), Button, Ericsson and Kvyat have joined Grosjean and Maldonado on track now.

08:48 Vettel's car has finally arrived back in the pitlane.

08:50 Kvyat had slipped to last after being the first man to set a time. He's now back up to sixth, joining a cluster of cars that are 0.7s down on Hamilton's benchmark.

08:51 Lots of work going on with Rosberg's car at the moment, which Mercedes has given a new name to this weekend:

"To recognize the importance of the new Hybrid era to both #F1 & @MercedesBenz our Silver Arrow has been rechristened as the “F1 W05 Hybrid!”"

08:52 Downforce has been a major talking point for McLaren since the Chinese GP. EDD STRAW's early trackside observations are that the car looks "decent" through Turn 3: "It's a bit hesitant on turn-in but once it's into the corner it's reasonably settled."

08:52 Jenson Button goes second fastest in the McLaren, just 0.020s slower than Hamilton. Alonso - with an overall best first sector - slots into third, just another 0.020s back.

08:53 Ricciardo takes top spot from Hamilton with a 1m27.973s.

08:54 The Red Bull's time at the top is short-lived. Button goes fastest by less than a tenth.

08:54 Button reports he "picked up understeer" on his fastest lap. "That's good news, that means it is probably doing what we expected," says his engineer in response.

08:55 Button and Ricciardo are both setting personal best sectors in the early part of the lap, as are Kvyat and Raikkonen slightly further down the order.

08:56 Mercedes explains what's causing Rosberg's lack of running:

"A few of you spotting @nico_rosberg's car cordoned off. The crew noticed something amiss with the ERS cooling system: investigation underway."

08:56 Neither of the top two turn those quick first sectors into better laptimes. Ricciardo pits, while Button stays out but can't improve.

08:57 Raikkonen makes a slight improvement to a 1m28.3s, taking him up to sixth.

08:58 BEN ANDERSON: "Not sure what to make of the lightweight Sauber. Doesn't look easy to drive - seems to be rolling a lot at the rear through Turn 3."

09:00 Just under half an hour to go, headlines so far:

* Button leads the way with a time of 1m27.891s, ahead of Ricciardo and Hamilton.
* Mercedes confirms Rosberg's car has a suspected ERS cooling issue.

09:02 Here's what EDD STRAW has made of the Red Bull and Ferrari performance through Turn 3 on more recent runs:

"Unsurprisingly, the Red Bull looks superb through here. The car rolls off the left lock out of T2 and turns into T3 in one move and carries good speed. The RB10 looks like it could take just about any line the drivers want.

"Alonso is struggling a bit more as the tyres go away. He's had a big wobble through Turn 2 and the car is moving around a bit in Turn 3. Controllable, but not the quickest."

At the moment Ricciardo is second, Vettel is 20th (having stopped early in the session), while Alonso is fourth and Raikkonen sixth.

09:03 "I have a brake failure!" shouts Giedo van der Garde as he approaches Turn 1. Fortunately no harm done, after a frightening trip through the run-off and a near-miss with the tyre wall on the left-hand side.

09:06 24 minutes remaining in FP1 and here's the current top 10: 1 Button; 2 Ricciardo; 3 Hamilton; 4 Alonso; 5 Rosberg; 6 Raikkonen; 7 Magnussen; 8 Maldonado; 9 Perez; 10 Kvyat.

09:07 Ricciardo, Alonso, Maldonado and Grosjean are the only cars on track at the moment.

09:08 Maldonado tops the lap count at the moment with 20. He's closely followed by Alonso (19), Magnussen (18), and Button (17).

09:09 Ferrari is bolting on a different front wing for Alonso to try out in the final 20 minutes of the session.

09:13 Modern drivers' approach to helmet designs is a regular cause for irritation in the AUTOSPORT office. Watching from trackside this morning has brought it to the attention of BEN ANDERSON:

"We have a raft of altered helmet designs for this weekend. That, allied to barely visible numbers on most of the cars, makes it difficult to tell team-mates apart as they flash by. Bigger numbers or consistent helmet designs please!"

In a less-ranty observation, Anderson tells us that "Magnussen is running out of rear grip now. He has a big slide coming out of Turn 3 but he held it like a rally driver".

09:22 Ricciardo is told that "GPS is poor," and that he will have be more aware of those around him during his final stint.

09:22 Hamilton was on course to go fastest by nearly one second, but he backed off in the final sector so didn't improve.

09:24 The track is busy in this final five minutes. Only Rosberg, Hulkenberg, Grosjean, Chilton and Vettel are in the pits.

09:25 Hamilton does go quickest this time, putting 0.7s between the Mercedes and previous pace-setter Button. The benchmark is now a 1m27.109s.

09:29 Hamilton reports his tyres are "really taking a beating," as several other drivers have been struggling for grip in this first session.

09:30 Just before the flag comes out, Hamilton pushes hard and manages a slight improvement to get down to a 1m27.023s (finding around 0.080s).

09:33 Here's how the top 10 stacked up in that first session:

1 Hamilton 1m27.023s
2 Button +0.868s
3 Ricciardo +0.950s
4 Alonso +1.105s
5 Rosberg +1.145s
6 Raikkonen +1.314s
7 Magnussen +1.400s
8 Maldonando +1.721s
9 Perez +1.756s
10 Massa +1.768s

09:36 Maldonado had the most productive morning with 34 laps under his belt. Vettel could only manage four laps before suffering an electrical issue, while Rosberg's ERS cooling problem only allowed him nine tours of the Circuit de Catalunya.

09:37 Stick with us on AUTOSPORT Live as we keep you up to date with everything going on in Spain between now and FP2.

09:42 Here's our comprehensive report from FP1, with Hamilton beating Button in the opening session of the 2014 Spanish Grand Prix:

button Hamilton leads first practice for Mercedes

09:49 Bottas sat out FP1 for Nasr again this morning, but the Finn isn't too bothered by the reduction in track time.

"We still have both cars driving in FP1, we can try different things in different cars and we still get the data," he said.

"If there are results that are not clear we can try again, but I don’t see that as any problem really and we should be immediately up to date after FP1."

09:50 Speaking of Nasr, he will be joining the rest of GP2 field for their 45-minute practice session that gets underway in just over 10 minutes. Busy boy indeed.

10:15 Fifteen minutes into GP2 practice and it's current points leader Jolyon Palmer who leads the way.

The Brit's best time so far is 1m30.448s, with Nasr and Stephane Richelmi just 0.2 seconds adrift in second and third respectively.

10:33 Just over 10 minutes remaining in this GP2 practice session.

The top three still remains Palmer, Nasr and Richelmi, while Mitch Evans and McLaren starlet Stoffel Vandoorne occupy fourth and fifth respectively.

One-second covers the top five at the moment.

10:46 GP2 practice done and dusted and the final six in that session were:

1 Palmer 1m30.448s; 2 Nasr +0.203s; 3 Richelmi +0.204s; 4 Evans +0.444s; 5 De Jong +0.503s; 6 Vandoorne +1.012s.

11:02 Vettel will miss the second practice session due to an electrical problem. Full story coming soon.

11:15 Here's our story about Vettel missing second free practice.

11:34 Simona de Silverstro completed her first F1 test for Sauber last month and the 25-year-old Swiss says she is now aiming to join the grid in 2015.

button De Silvestro targets F1 race seat

11:56 The second practice session is due to get underway in five minutes. One man we will be keeping an eye on is Rosberg, who only completed nine laps in FP1 due to an ERS cooling issue.

12:01 Drivers are currently being strapped into their cars for their installation laps. Apart from Sutil that is, whose Sauber doesn't have its engine cover on at the moment.

12:02 Drivers are progressively leaving the pitlane to complete their installation laps.

12:04 Ericsson is the first man to complete a full lap. He's followed by Grosjean, who goes nine seconds faster to take to the top.

12:05 Replays show Ericsson wrestling his Caterham and running wide at Turn 3.

12:05 Grosjean's team-mate Maldonado goes quicker - 1m29.275s - to jump up to P1.

12:05 Chilton is advised that he has an engine problem. "Come in slowly, please," asks his polite engineer.

12:07 Caterham provides us all with the current temperatures:

"Track temp is now 44c (twice what it was in FP1) and air temp is up to 23c"

12:07 Over half the field has been out on track already. Maldonado still leading, now from Magnussen's McLaren and the Toro Rosso of Kvyat.

12:09 The first 1m28s lap put Magnussen on top of the times, but he's quickly outpaced by team-mate Button with a 1m28.703s.

12:09 Guiterrez and Maldonado have had moments through Turn 3 - the Mexican having the more spectacular, with a bit of four-wheel drifting.

12:10 Raikkonen, Alonso, Massa and Hulkenberg (and obviously Vettel) are the only men yet to complete a lap.

12:11 Montezemolo is in the Ferrari garage overseeing things at the moment. Alonso has yet to set a time.

12:12 Hamilton is back at the head of the times with a 1m27.448s. He's now leading from Ricciardo, two tenths of a second slower.

12:12 BEN ANDERSON: "Just had a chat with Williams reserve Felipe Nasr, who drove Valtteri Bottas' car in FP1 and set the 14th fastest time.

"He looked a bit frazzled having dashed from the F1 paddock to perform his GP2 practice duties!

"He reckons Williams has taken another step forward with the FW36 in Spain, though it's still lacking some rear end grip at high speed.

"He says some set-up experiments prevented him getting closer to team-mate Felipe Massa on the timesheet in the later part of the session."

12:12 The Mercedes driver's best is still some four tenths off his best from this morning.

12:14 Two purple first sectors suggest Hamilton is about to go even quicker.

12:15 And so he does. Hamilton completes a lap of 1m27.061s, matching his morning pace.

Ferrari garage12:16 AUTOSPORT magazine Editor CHARLES BRADLEY was in the F1 pitlane just before practice started, and he tells us that Fernando Alonso's car "started to burn" just before the session.

"It caused some mild panic but only for a minute or so. You could briefly see some smoke, too."

12:16 Rosberg makes sure Mercedes is comfortably on top, moving into second place. Ricciardo is the only other man in the 1m27s.

12:17 As his boss Montezemolo waves to the crowd from the pit wall, local hero Alonso jumps up to fourth, but nearly a second behind Hamilton.

12:18 Plenty of motorsport happening around the world this weekend, as well as following F1 as it happens on AUTOSPORT you can also keep up with Rally Argentina - both with radio commentary from WRC Live and text updates from AUTOSPORT Race Centre Live

12:19 Rosberg has improved his time to close in on Hamilton's best. The German is now less than three tenths off his team-mate's pace.

12:20 Most of the drivers have returned to their garages, ready for a debrief before embarking upon their short runs on the medium compound rubber.

12:20 Only Chilton and Sutil are yet to set a time (again, apart from Vettel). The German Sauber driver is watching the action from the garage while the team works on his car.

12:23 Few drivers on track at the moment. The 10 quickest men are in the pits.

12:24 Except Maldonado (P10), who is now back out in the Lotus.

12:25 Pastor Maldonado has become the first to head out on the medium-compound Pirellis. Improved from a 1m29.275s to a 1m27.866s. So that suggests plenty of time in the quicker compound.

12:26 Chilton returns to the pitlane after being told to come in again. Sounds like he's experienced another engine issue.

12:28 Raikkonen complaining about the lack of grip, something common among most drivers today. The Finn is sixth quickest at the moment.

12:30 Half an hour in and the main developments so far:

* Hamilton leads Rosberg at the top of the timesheets with a 1m27.061s.
* Sutil missed the first 20 minutes as mechanics attended to his Sauber.
* Chilton has suffered two engine issues and is the only driver not to set a time.

12:30 Montezemolo enjoying the fans' attention, clapping in the pitlane after a short visit to Mercedes' garage.

12:31 Third-fastest Ricciardo is back on track. Seven laps so far for the Australian.

12:32 EDD STRAW: "Ricciardo is now out on the medium Pirellis. Expect to see him hit the top of the timesheets imminently as both Mercedes drivers are in the pits and yet to run the quicker tyre. Ericsson, Bianchi and Kobayashi are also on the mediums, as is Maldonado."

12:32 Sutil has completed his first timed laps and is up to 14th position. Chilton is the only man without a time.

12:33 Ricciardo jumps up to P1 with the quickest time of the weekend: a 1m26.509s using the medium compound.

12:35 The Red Bull driver found a full second with the softer compound. Mercedes' drivers are yet to run with that tyre.

12:36 EDD STRAW: "Raikkonen has also gone out on the mediums now. Judging by the improvements we've seen so far, might be able to move up to second temporarily with a good lap. He needs to find just over a second to get ahead of Hamilton."

12:36 Simona de Silvestro watches on from the rear of the Sauber garage. She is targeting a place on the F1 grid next season.

12:37 Hamilton, Rosberg and Alonso out on track now.

12:37 All of them using the softer tyres, so you can expect a Mercedes back on top in a moment.

12:37 EDD STRAW: "We're seeing most drivers on a conventional programme in this session. That's usually some running on the harder tyres, then switch to the softer rubber for a quick lap followed by some vitally-important long-run work."

12:38 Purple in S1 and S2 for Rosberg. Purple in S1 and S2 for Hamilton too.

Hamilton12:39 A 1m25.973s for Rosberg. A 1m25.524 for Hamilton.

12:40 Hamilton's flyer puts him nearly half a second ahead of his team-mate and nearly a full second ahead of Ricciardo.

12:40 Alonso also improved his time to move up to fourth, albeit 1.5 seconds off Hamilton's pace.

12:41 The Ferrari driver is going for another lap, but the medium tyre is unlikely to help him improve after the first flyer, when the rubber is peaking.

12:42 Lotus mechanics come running to Grosjean, who has stalled at the end of the pitlane.

12:42 Indeed, no improvement for Alonso. Team-mate Raikkonen is now fifth ahead of Maldonado, Kvyat, Hulkenberg, Button and Magnussen, who completes the top ten.

12:45 We reach the halfway point of the session, and Mercedes' gap suggests the fastest times are unlikely to change much (unless Hamilton and Rosberg improve).

12:46 Grosjean's E22 has been pushed back in to the Lotus garage and, after a quick check, is back out and running once again.

12:47 EDD STRAW: "Interesting to note that the current top six - Hamilton, Rosberg, Ricciardo, Alonso, Raikkonen and Button - have ended up in exactly the same order on their medium-tyre runs as they did on their hard runs. The average improvement in laptime using the quicker tyre for the top six is 1.076 seconds. The biggest improvement was by Hamilton, who went 1.537s faster."

12:48 The short runs done, most drivers are back in the pits. Longer runs expected soon.

12:48 BEN ANDERSON: "Sutil splits a Toro Rosso and a Williams on his last lap. Perhaps the lightweight Sauber is a significant step forward for the small Swiss team?"

12:49 "Engine problem! It seems to be the same problem as this morning," says Grosjean over the radio.

12:51 Ricciardo is starting another lap, this time using used medium tyres. Rosberg is back out too.

12:53 Chilton is the last man to put on medium tyres. The Briton is down in 19th.

12:55 Chilton's medium tyre run isn't going so well as replays show he lost his monkey seat while running over the kerbs at Turn 16,

13:00 Ricciardo continues to run with the medium tyres, but his times are from for his best. His latest is over six seconds off the pace. It's the eighth lap of the run.

Renault13:01 Renault has promised more speed from its power unit after some teams complained of a lack of grunt against the Mercedes-engined cars.

That recovery could be compromised, however, by late payments from those that have been doing the complaining!

button Renault reveals that some of its F1 teams are late with payments

13:01 There appears to be a big and quick drop-off in performance with the mediums. It will be interesting to see how many pitstops are needed on Sunday.

13:04 Alex Wurz gives a detailed analysis of the current tyre situation within 140 characters:

"Very large tyre deg here. Compromise between high+medium speed understeer vs low speed rear degradation... glad I am not a tyre!"

13:04 Thirteen laps for the set of tyres Ricciardo is currently using. He is lapping over seven seconds off the pace now.

13:05 Maldonado's mediums, meanwhile, are 22 laps old and he is lapping in the 1m34s, nearly 10 seconds off Hamilton's fastest time.

13:06 Ricciardo radioed in a moment ago to say the balance of his car was "a bit more neutral," which would suggest Red Bull has solved his understeer issues.

13:07 Rosberg's mediums are on 11 laps, and he's currently on a seven-lap stint. A 1m33s was his last.

13:08 Hamilton's run seems much stronger, the Briton lapping in the 1m30s after six laps.

13:10 On lap four of his run on hards, Alonso has just posted a 1m33s.

13:11 Less than 20 minutes of the session left. With everyone doing long runs, there are no changes in the classification.

13:13 Maldonado is asked how his tyres are doing. "Completely finished!" comes his response.

13:15 Nine laps for Raikkonen on the current stint. The Finn lapping quite consistently in the 1m32s.

13:17 Alonso is still out on hards, doing similar times.

13:18 All cars except the Sauber of Gutierrez (and Vettel) are on track with less than 12 minutes left.

13:20 Grosjean is told his brakes are "not safe" and is told to come in due to abnormal brake wear.

13:20 Hamilton's run is nothing but impressive. Still doing 1m30s.

Can anyone stop him this weekend? Stay tuned for our Friday form analysis later on to find out.

13:22 The busiest man so far has been Maldonado, about the complete his 40th lap of the session.

13:23 Sixteen laps on the medium tyres so far for Hamilton as Rosberg fits the hard ones for the final minutes of the session.

13:24 "It's unbelievable how low the grip is," says a rather despondent Hulkenberg. He's currently 11th quickest.

13:24 BEN ANDERSON: "Ominous signs for the rest of the field at the moment. The Mercedes still appears to have a second in hand on long runs and on one-lap pace so far..."

13:26 Bad news for Maldonado, who is told: "OK Pastor, we may have a gearbox failure, so please box this lap."

13:26 Vergne has stopped at Turn 3 having lost his right rear wheel.

13:27 Three drivers - Chilton, Kobayashi and Ericsson - slower than the fastest time in GP2 practice.

13:27 Yellow flags are waving and the Toro Rosso will need to be recovered. Replays show the Frenchman lost the wheel at the exit of Turn 1.

13:29 A minute left in the session, and this is basically all over as Vergne's car is recovered.

13:30 Chequered flag is out.

13:31 Drama at the end of the session as Chilton has gone off at Turn 4. He managed to come to a halt before reaching the tyre barrier.

13:33 Here's the top 10 at the end of the second session:

1 Hamilton 1m25.524s
2 Rosberg +0.449s
3 Ricciardo +0.985s
4 Alonso +1.597s
5 Raikkonen +1.772s
6 Magnussen +2.264s
7 Button +2.287s
8 Massa +2.300s
9 Maldonado +2.342s
10 Kvyat +2.525s

13:35 Despite suffering a few issues in that 90-minute session, Maldonado had the most productive afternoon with 42 laps.

13:44 Our full report from the second practice session is now available for you to read:

button Hamilton stays on top in FP2

14:11 Hamilton admits he has been surprised by how long he could make the medium tyres last during practice.

"They didn't seem so bad. When they told me I had to do 14 laps on the option tyre I was like 'you're crazy, that's not going to happen' but I think I did more than that. It's surprisingly a lot better."

But he stopped short from predicting a two-stop race on Sunday.

"I don't know. It's not impossible. I've not really thought about it."

14:35 On the day Mercedes has announced its car will now be called F1 W05 Hybrid, the team admits it was the hybrid system that hindered Rosberg during first practice.

The issue was solved and both cars ran without problems in the afternoon.

14:43 JONATHAN NOBLE has been hearing from the Red Bull drivers, and Daniel Ricciardo is - by his standards - pretty gloomy about the advantage Mercedes is showing today:

Ricciardo frustrated by Mercedes gap

14:49 Here's a bit more from Ricciardo, specifically on the setback for the team of only one Red Bull completing any meaningful running today:

"Obviously it is a concern. We don't learn so much by not having two cars on track. Coming here with the updates, it would be nice to test some new parts on each car.

"Fortunately my day went well, we have a lot of data to look at on one car, but it's nice when two are circulating. Now, as a team we have to use all the data we can and try to get back track time."

15:05 Jenson Button was second fastest in morning practice and fell to seventh in the afternoon.

Which result best reflects McLaren's Barcelona pace...?

Here's a hint from Button:

"I had a friend call me this morning who's been in motorsport 14 years and he said 'is it as good as it looks?' and I replied 'mate... come on, it's practice, you know better than that...'"

More of Jenson's wisdom in our news section shortly.

15:24 Over the next couple of hours on AUTOSPORT's news pages we'll round up the remaining news stories and bits of paddock reaction to today's practice sessions, and GARY ANDERSON and EDD STRAW will be number-crunching their way to our practice form guide to give some hints of how Sunday's race might shake out.

Race Centre Live will be back from 6.30pm UK time with coverage of the Friday afternoon loop of Rally Argentina stages and qualifying for IndyCar's first Indianapolis road course race.

Our F1 GP Live coverage will be back at 9.30am on Saturday morning ready to take you through final practice and qualifying in Spain.

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Friday 09 May Start GMT
 Friday - Practice 07:30
Saturday 10 May
 Saturday - Qualifying 08:30
Sunday 11 May
 Sunday - Spanish GP 10:30