14:55 Hello everyone and welcome to AUTOSPORT Live for coverage and rolling updates from the penultimate round in this year's FIA Formula one world championship.

The sport heads back to the United States for the first time since 2007, to a brand new facility - the Circuit of the Americas just outside Austin, Texas, giving the teams a clean sheet of paper to work with.

Reaction to the new track has been extremely positive so far, but the proof of the pudding is about to be encountered. Practice begins in just under five minutes time and, as always, the tasks will include completing an installation run, then working on some aerodynamics tests, before moving on to baseline set-up and putting laptimes on the board.

14:56 Here's how the standings look with two races remaining:

World Championship standings, round 18:                

Drivers:                    Constructors:             
 1.  Vettel       255        1.  Red Bull-Renault          422
 2.  Alonso       245        2.  Ferrari                   340
 3.  Raikkonen    198        3.  McLaren-Mercedes          318
 4.  Webber       167        4.  Lotus-Renault             288
 5.  Hamilton     165        5.  Mercedes                  136
 6.  Button       153        6.  Sauber-Ferrari            124
 7.  Massa         95        7.  Force India-Mercedes       95
 8.  Rosberg       93        8.  Williams-Renault           73

14:57 Weather conditions are fine and dry at the 5.513 km track with largely clear skies and plenty of sunshine - although it is pretty cold.

It will remain dry with minimal cloud around during the two upcoming sessions, while a light north-easterly breeze will blow and air temperature will climb to 20 degrees Celsius.

14:58 Medium and hard compound tyres are the selection for the first race at the all-new Austin venue, with drivers handed an additional set of the harder rubber for this first practice session.

Initial running is often dented by the sole allocated set of tyres for each driver, so the extra rubber will be a welcome boost for teams looking to explore the new track.

"We've chosen the hard and the medium compounds as we think it will be quite a demanding track, based on the asphalt samples and simulation data we have gathered," said Pirelli's Paul Hembery.

"Naturally we've leaned towards a slightly more conservative choice in order to cover every possibility at a brand new circuit, but the tyre choice in Abu Dhabi was also conservative and yet we saw one of the most exciting races of the year."

0 min: Track temperature is a rather chilly 18 degrees as we wait to see who will christen the new circuit in an official session.

0 min: Practice is underway in the USA.

0 min: Abu Dhabi winner Raikkonen in his Lotus is leading the cars out of the pits.

1 min: Di Resta heads out among the early runners in the Force India.

1 min: Massa heads out in his Ferrari to put an installation lap on his machine.

2 min: Vergne, Ma Qing Hua, Ricciardo, Senna, Maldonado, Webber, Vettel, Hulkenberg and Rosberg are all on track to sample the circuit.

3 min: Wobbles already for Glock and Kobayashi as they discover which way the circuit goes.

3 min: Massa tells his team that the track is very slippery at Turn 1.

3 min: Hua is of course taking the place of Karthikeyan in the HRT for this session. The Indian will be back later to take his race car for the rest of the weekend.

3 min: Massa continues into a second tour to further evaluate the slippery new asphalt.

4 min: Many of the early runners are back into the pits after a single installation lap.

4 min: De la Rosa and Schumacher are among the last to head out onto the track.

5 min: Webber and Vettel have both come through the pitlane and back out onto the new circuit.

5 min: Massa slides sideways at Turn 11 as he heads back to the pitlane.

6 min: Maldonado is another to come round for a second lap of the circuit.

7 min: The track is just 19c this morning and one factor in the lack of grip is the difficulty building heat in the harder compound tyres.

7 min: Hulkenberg reports on the team radio that the track is so slippery, like he would normally find on a wet circuit.

8 min: Rosberg heads out of the Mercedes garage to begin a second run, following the installation.

9 min: As with all new circuits, the asphalt is also fine-grained and very smooth, limiting the energy that it puts into the tyres.

10 min: Hamilton continues on an installation effort in his McLaren, reporting very dirty track conditions.

10 min: Rosberg completes one slow lap and comes back into the pitlane.

12 min: With Hamilton back into the pits, the circuit is empty for the moment.

12 min: Hamilton, sporting a US-themed helmet design this weekend, returns to the pits after a slide around the circuit.

14 min: Kobayashi breaks the silence and resumes in his Sauber.

15 min: Bruno Senna heads out for some more exploratory laps in the Williams.

16 min: Kobayashi oversteers around the final corner and crosses the line to begin an attempt against the clock.

17 min: Having all the grip of slicks on a wet circuit, Kobayashi continues to wrestle his Sauber around the lap.

18 min: Understeer this time for Kobayashi through the final corner but his inaugural time is a 1m54.846s.

18 min: Vergne joins the early brave souls on track for some rallycross action.

18 min: Ricciardo is next out in the other Toro Rosso.

18 min: Plenty more time to come as some rubber goes down on the surface and some of the construction dust is cleared from the racing line.

19 min: Webber is another to leave the garage and join the racetrack.

19 min: Senna posts 1m56.291s to slot in behind Kobayashi.

20 min: Kobayashi finds more grip on his second attempt and improves to a 1m51.228s.

21 min: Senna improves on his second timed lap to 1m53.227s. He moves back into second spot.

21 min: Raikkonen joins the order with an initial 1m53s effort as Kobayashi makes the benchmark a 1m48.517s.

22 min: Vergne joins the fun with a time of 1m59.055s to slot in seventh.

23 min: Webber goes second in the Red Bull with a time of 1m49.870s.

24 min: Vettel, di Resta and Maldonado are also on track for a first run.

24 min: Perez is trying for a time in his Sauber now, going fifth fastest in 1m51.325s. The Mexican has lots of support on hand this weekend.

24 min: Webber moves to the front of the field with a lap of 1m48.182s.

25 min: Kobayashi makes the time to beat a 1m46.960s before an off at Turn 17 on his next attempt.

25 min: Senna has improved his time with a lap of 1m48.713s. He is up to third spot, behind Kobayashi and Webber.

25 min: That's over five seconds that Kobayashi has shaved off his best as he gets more comfortable with the grip levels and pushes on.

27 min: Webber improves and is just 0.052s down on Kobayashi now with a time of 1m45.918s.

27 min: Kobayashi takes back the leading time with a new best of 1m45.866s.

27 min: Vettel is on the board with a time of 1m51.162s, as he finds his feet with the new circuit.

28 min: Schumacher and Rosberg are on track after lengthy stops in the pits.

29 min: Vettel moves up to fifth with a lap of 1m47.735s.

29 min: Raikkonen, now fourth fastest, improves to a 1m47.306s as he tests further revision to the Lotus exhaust package.

30 min: Webber moves back to the head of the list with a time of 1m44.839s.

30 min: Hamilton is heading out for a run, as is title contender Alonso.

30 min: Di Resta also improves and the Scot is into third spot, behind Webber and Kobayashi with a time of 1m46.621s.

31 min: Rosberg's first effort places him sixth with a time of 1m47.264s.

32 min: Plenty of cars on track at the moment with teams taking advantage of the additional set of hard tyres given to each driver.

32 min: Schumacher joins the party in 11th place with 1m50.075s, as he explores the Circuit of the Americas for the first time in anger.

33 min: Vettel locked up at Turn 19 but was able to continue via the run-off area.

33 min: Webber has lowered the benchmark by around eight-tenths of a second, with 1m43.672s. He is now 1.577s clear of Kobayashi, with di Resta third.

34 min: Hamilton slots in 12th fastest with an initial timed effort.

34 min: Vettel gets a better lap next time around and posts 1m44.233s to move into second place.

34 min: The Ferrari pair are around six seconds off the pace at this stage as they build confidence around this new track.

35 min: Hamilton heads up the massive hill to Turn 1 after clocking a 1m44.252s to go third fastest.

37 min: Hamilton is pushing the limits of grip in his McLaren now, topping the times with a new best of 1m42.603s.

37 min: That puts Hamilton over a second clear at the top as he enjoys getting up to speed with the Austin circuit.

38 min: So it's Hamilton up top now with Rosberg into second with 1m43.331s, Vettel now third after posting 1m43.409s and Webber fourth.

39 min: Alonso jumps to the top of the order with a new benchmark in his Ferrari - 1m42.538s.

40 min: Hulkenberg has spun at Turn 1 after taking a wide entry into the tight left-hander. He was able to rejoin without any damage to the Force India.

41 min: Hamilton makes a big step forwards with a lap of 1m40.918s.

41 min: Rosberg comes round and registers another improvement. He moves into second with 1m42.131s.

42 min: Vettel is back on track after a short stay in the pits.

42 min: Alonso improves with a 1m41.365s, closing to under half a second off the latest Hamilton benchmark.

43 min: Hamilton leads the pack with a time of 1m40.918s. He is 0.447s clear of Alonso, with Rosberg third, Vettel fourth and Button up to fifth.

43 min: Massa is sixth in the other Ferrari, ahead of Webber seventh, Grosjean eighth, Schumacher ninth and Hulkenberg rounds out the top 10.

43 min: Button clocks a 1m42.959s to go fifth fastest.

45 min: Perez explores the boundaries of the pitlane entry, finally making it back to the garage in his Sauber.

45 min: Turn 19, the penultimate bend, continues to catch out the drivers with Massa the latest man to venture out to the run-off.

47 min: Alonso is back on top again with an improved best of 1m40.603s, with Hamilton now three tenths slower after a further improvement.

47 min: Schumacher has climbed up the order to fifth place with a time of 1m42.647s in the Mercedes.

48 min: Grip levels continue to build, with drivers complaining a lot less about track conditions as rubber goes down on the surface.

49 min: Hamilton was on for another improvement but joins the list of victims at the developing trouble spot of Turn 19.

49 min: Webber rejoins the circuit to begin his second meaningful exploration run around the circuit.

50 min: Button finds more in his McLaren to go third fastest with a 1m40.965s, just fractions off Hamilton's best.

52 min: Hamilton clocks 1m40.175s to put his McLaren back on top of the ever-improving times.

53 min: Little running so far from the HRT drivers. Hua has completed an installation lap and a short seven lap run, but de la Rosa has yet to appear after his installation lap.

53 min: Little in the way of tyre wear from this ultra-smooth surface, with the rubber still looking very fresh on Hamilton's car as he pits.

54 min: A one-stop race already looks likely, with the hardest possible compound allocation appearing to be pretty conservative.

55 min: Webber comes round to complete another lap and he moves up to fifth spot with 1m42.378s.

57 min: Di Resta logs an improvement and he is fifth with 1m42.289s.

58 min: Hamilton leads McLaren team-mate Button so far, with Alonso 0.428s back in third, Rosberg fourth, di Resta fifth and Webber in sixth spot.

58 min: Ricciardo improves and moves up to 17th position with a time of 1m44.694s.

59 min: Kobayashi is up to fourth in the Sauber after posting a lap of 1m41.766s.

59 min: Alonso heads out for a second run in his Ferrari.

60 min: De la Rosa is now on track in the HRT. He is working through his first timed lap of the weekend after a lengthy stay in the pits.

60 min: Button complains of some front left graining on his detailed report back to the team, which may be a symptom of the cold conditions.

60 min: Hulkenberg posts a minor improvement. He is 16th with a time of 1m43.984s.

61 min: Webber moves back up the list to fifth spot with a time of 1m41.470s.

61 min: De la Rosa completes that timed lap and he is finally on the board in 23rd with 2m02.915s.

62 min: Maldonado improves to eighth position in the Williams with a lap of 1m42.539s.

62 min: A defined racing line is appearing on the track surface, with things still very slippery when drivers run wide.

63 min: Plenty of improvements mid-pack with Raikkonen, Grosjean, Massa and Perez all going faster.

64 min: Kobayashi improves to fourth fastest and may have switched to his second set of hard compound tyres having pioneered some of the early laps.

64 min: Schumacher fights the Mercedes through the penultimate corner but just keeps control of the car. He completes the lap and is 11th with 1m42.588s.

65 min: De la Rosa is taking chunks off his time as he learns the circuit. He is still 23rd, but now with a time of 1m57.607s.

66 min: Vettel has slipped down the order somewhat to 12th position. He is now on track and was looking set to improve, but lost time in the second sector.

67 min: Vettel gets back on it in the third sector and logs a slight improvement of 1m42.454s. He is up to 10th spot.

67 min: Massa improves his best to a 1m42.142s, going seventh fastest.

68 min: Hulkenberg also finds a slight improvement and moves up to 14th with a time of 1m43.290s.

68 min: Vettel continues to find pace and he is up into fourth place with 1m40.978s.

68 min: De la Rosa is down to 1m53.207s but he remains in 23rd position, some way off Pic's Marussia.

70 min: Both McLaren drivers are back on track while Alonso sets the fastest first sector time.

70 min: Ma Qing Hua is back out for another run in the second HRT entry. He is now into a timed lap.

71 min: Alonso backs off to find space and heads into another timed attempt.

72 min: Vettel continues his rise up the timesheet and he is second only to Hamilton with 1m40.335s. The gap between them is 0.160s.

72 min: The Spaniard is enjoying the sweeping curves of the first sector, again topping the time in the exciting early part of the lap.

72 min: Alonso clocks a 1m40.337s, putting him back up to third fastest.

73 min: Di Resta heads out to begin another run with just under 17 minutes of this first session remaining. He is rounding out the top 10 for now.

74 min: Hamilton finds a fraction more with the benchmark time now set at 1m40.116s.

75 min: Kovalainen goes for a spin in his Caterham, looping around heading out of the early sweepers at Turn 9.

76 min: As with all new circuits, there's little penalty for a spin and Kovalainen is underway again.

77 min: Rapid work going on around the car of Ricciardo, as the Toro Rosso mechanics move quickly to get him out for a final run.

77 min: Hamilton is told he is 0.2s down on Alonso in the first sector but McLaren is optimistic that this relates the Spaniard's use of fresh tyres

78 min: Kovalainen returns to the Caterham pits and unsurprisingly reports that the car is nervous, with oversteer, in the low speed corners.

79 min: Meanwhile, Hamilton further improves in the first sector to make the best a much quicker 1m39.687s.

79 min: Webber has spun on his latest lap at Turn 8. He stopped sideways but was able to continue.

80 min: Michael Schumacher has likewise suffered an off-track excursion at Turn 11 after running onto the extra tarmac. He found his way back to the prepared surface and was able to continue.

80 min: Vettel is back on the circuit for a final run, with just under 10 minutes of the session remaining.

81 min: Hamilton continues to top the list with a time of 1m39.687s, 0.648s clear of Vettel, with Alonso third and Button in fourth spot.

82 min: Hamilton now tops the final sector time as he again improves the leading time - now a 1m39.670s.

83 min: Hulkenberg moves up the order to 11th place with a time of 1m42.443s in the Force India.

83 min: Massa again takes to the extremely popular line off into the boonies at Turn 19.

84 min: Meanwhile, Hamilton's progress continues with a new best of 1m39.543s.

84 min: Only three drivers in the garage in the final minutes - the HRT duo and Bruno Senna - with everyone else circulating and gathering more data.

85 min: Senna heads out for his final run of the morning sesssion, leaving the HRT pair as the only occupants in the pitlane.

85 min: Vettel posts the fastest middle sector as he looks to push Hamilton in the final stages.

85 min: But the German ultimately does not improve after a slow end to the lap.

86 min: Raikkonen makes some progress in his Lotus, clocking 1m41.880s to go eighth fastest but still over two seconds off Hamilton's best.

86 min: Hulkenberg improves yet again. Not long ago he was down in 16th, but he is up to eighth with a time of 1m41.519s.

87 min: More speed for Massa as well, going sixth in 1m40.966s.

87 min: Vettel moves ahead of Hamilton and tops the list with a time of 1m38.692s.

88 min: Vettel puts 0.851s between himself and the Briton, with Alonso a whopping 1.645s back in third position. Button is fourth.

89 min: Hamilton has been into the pits, possibly for a change of tyres, and will be looking for a late response to that new benchmark.

90 min: First practice draws to a close as the flag comes out.

16:30 Webber registers a slight improvement on his final timed lap. He remains in fifth with a time of 1m40.650s.

16:31 Hamilton has pitted again, leaving Vettel to comfortably take the leading time.

16:31 But Vettel does it again and takes another chunk off the benchmark with 1m38.125s to move well clear of the pack on his last lap.

16:32 Raikkonen, meanwhile, had been ordered in for pitstop practice but didn't make the exit light and has been forced to abandon his Lotus.

16:32 Webber returns to the pits and the mechanics work through a practice stop, before wheeling the Australian into the garage.

16:33 They quickly get ready for Vettel and repeat the test. Meanwhile, more fluid is leaking from Webber's car as he is pushed in.

16:33 So after all that, Vettel heads the pack at the end of first practice at the all-new Circuit of the Americas, with a time of 1m38.125s.

16:34 The German is some 1.418s clear of Hamilton, with Alonso more than two seconds back in third. Button is fourth with Webber fifth.

16:35 Massa is almost three seconds down on the flying Vettel in sixth spot, ahead of Hulkenberg seventh and Kobayashi in eighth.

16:35 Rosberg is ninth in the Mercedes and the man with the most fans expected here this weekend - Sergio Perez - rounds out the top 10.

16:36 Other notables: Michael Schumacher ended the session down the list in 17th position, more than four seconds off the benchmark time.

16:37 The drivers have had their first taste of the new facility. Join us later for second practice action from Austin.