2017 American Formula 1 Grand Prix - First free practice

17:32
That concludes our coverage of the first session - stay tuned to GPUpdate.net for all the latest; we'll be back for the second session, at 14:00 local time
17:31
It's Lewis Hamilton who ends the session quickest, half a second clear of Sebastian Vettel
17:31
Gelael has had his second excursion of the session - he has a very slow speed spin at Turn 19. Oh dear...
17:30
The chequered flag comes out, bringing the opening session to a close
17:29
Leclerc has a moment through Turn 19 and pops his Sauber over the kerb
17:28
Vandoorne moves into fifth position for McLaren on the Ultra Softs
17:27
17:27
Grosjean, though, backs off, and that enables Verstappen to move ahead
17:26
Verstappen is requested to clear Grosjean - but if anything, drops further behind the Haas
17:24
Verstappen has a moment of oversteer through Turn 19 and takes to the run-off - a conventional approach for that tricky left-hander
17:22
Despite McLaren's earlier communication, Alonso is out on track, sporting his Indy 500-themed lid
17:20
17:19
Drivers are still circulating on slick tyres, though, as the session winds towards a conclusion
17:15
A few drivers are reporting some more spots of rain - with 15 minutes left, that could be it for quick times
17:14
17:13
Hamilton locks up again and goes deep into the final corner, utilising the expansive run-off
17:12
Vettel jumps above Bottas into second spot, but is still 0.593s behind Hamilton
17:12
"The only problem I have is that the helmet is still lifting", Hartley informs Toro Rosso
17:11
Hamilton also had a lock-up into Turn 1, but rolled off the brakes, limiting the damage to the rubber
17:10
"We need to box, two big flat spots," says Bottas, which explains the vibrating rear end
17:10
A replay shows he suffered a substantial lock-up into Turn 1, flat spotting both front tyres
17:09
We have a slow Mercedes - Bottas is touring, with his rear wing slightly wobbly...
17:08
Hamilton improves on his best lap, moving him onto a 1:36.335 - a gain of exactly six-tenths
17:08
Only Massa, Vandoorne, Magnussen and Leclerc have yet to set a slick time
17:06
17:06
Bottas now slots into second - just 0.044s behind his team-mate
17:05
Verstappen responds to Hamilton's effort - but falls 0.404s short of demoting the Briton
17:04
Hamilton knocks a fair bit off the best time - he gets down to a 1:36.935, also on Super Softs
17:03
17:02
Verstappen demotes his team-mate with a 1:38.158, on the Super Soft tyres
17:01
Stroll moves into second place - Ricciardo's earlier time is coming under more threat
17:00
Raikkonen has moved into second, with Hulkenberg in third place
16:59
16:59
Expect the order to rapidly change across the next few minutes, with an array of efforts being set on slicks
16:58
Hartley vaults up to second - 2.6s behind good friend Ricciardo
16:57
Ricciardo gets down to a 1:39.366 on his next lap - going purple in all three sectors
16:56
McLaren is investigating a hydraulic leak on Alonso's car...
16:56
Hartley is out for his first taste of the Ultra Soft tyres
16:55
16:54
Vettel's car is up on the jacks - is that more woe for Maranello?
16:53
Ricciardo sets a time of 1:40.297 - that's five seconds clear of Vettel's earlier effort
16:53
The pace is also rapid through the middle sector
16:52
Ricciardo flies through the first sector on Super Softs and is almost a second quicker than Vettel's benchmark
16:51
Ricciardo ends the silence and returns to action
16:51
16:46
Only Ferrari's title contender clocked his time on the slicks though...
16:46
The current order: 1 VET 2 MAS 3 VER 4 VAN 5 SAI 6 OCO 7 STR 8 HUL 9 HAM 10 RIC
16:44
The remaining half of the session should be more representative, after the initial damp running
16:43
We're into the usual 40-minutes-in lull, with just a handful of drivers lapping
16:39
16:39
Raikkonen, meanwhile, skates wide through Turn 19, as Sauber tester Leclerc complains of understeer
16:38
Vettel goes quickest - a 1:45.960, despite backing off through the final couple of corners.
16:37
Vettel, on a set of Super Softs, is lighting up the timing screens
16:35
The switch to slicks is being made as the circuit gradually gets drier
16:33
Hartley has put his first timed lap on the board - he's 14th, ahead of Gelael
16:33
Massa displaces Vettel in second spot, 0.249s behind Verstappen
16:31
Sainz Jr. goes up to fifth as he gets to grips with his new surroundings
16:28
16:28
Vettel moves into second spot, 0.350s behind Verstappen
16:27
We're gradually getting more times on the board as the circuit begins to dry up
16:26
Here's a shot of Ricciardo getting it wrong earlier
16:25
Verstappen surges clear with a 1:47.922 - that gives him a two second buffer up front
16:24
Vandoorne slots into second - just 0.023s behind Hamilton
16:23
16:21
Ocon is the latest to find trouble - he spins exiting Turn 19
16:19
16:19
Gelael's STR12 shot towards the inside of the circuit and he stumbled across the grass before recovering to the black stuff
16:18
Gelael has had a moment after he dipped a wheel onto the kerb exiting Turn 15
16:17
But he spins after taking too much kerb through the exit of Turn 9!
16:17
Ricciardo clocks the best time through the first sector in the RB13
16:16
Verstappen returns to the pits, leaving just Ricciardo and Gelael on track
16:12
The final sector, though, is not an improvement, and he stays second overall
16:12
Verstappen is up on Hamilton's benchmark after the first two sectors
16:11
16:09
Hamilton has edged ahead of his team-mate on a 1:50.146, with only four drivers on the leaderboard
16:07
16:07
Bottas' exploits through T19 came on his and the weekend's first timed lap - a 1:50.529
16:06
Bottas is having some fun early on! The Finn slides through the tricky Turn 19, proper WRC style...
16:05
A replay shows that the big bump along the back straight - where one of the DRS zones is located - is still present, despite efforts year-on-year to smooth the surface
16:04
Sainz Jr. is out on track as he gets to grips with the Renault R.S.17 for the first time
16:03
It's just an installation lap for the drivers so far in damp conditions
16:02
16:02
Pirelli has made one set of its prototype Intermediates available for each driver today
16:01
Drivers have headed out on the Intermediate compound - some on the green-banded ones, others on the unmarked, indicating that they are Pirelli's prototype versions
16:01
A handful of drivers are running with the halo device, ahead of its introduction into the sport in 2018
16:00
The green light comes on - and F1 is underway at COTA for another year
15:58
McLaren's Vandoorne is already waiting at the end of the pit lane for the session to begin
15:58
Air temperature is at 19°C this morning, with the track barely warmer at 23°C
15:57
15:57
Formula 1 has linked up with the Susan G. Komen foundation and there are splashes of pink around the paddock, circuit, and on the cars and drivers
15:56
However, in a tweak, the Ultra Soft has been coloured with a pink sidewall, as part of Formula 1's attempts to raise awareness of Breast Cancer this weekend
15:55
Should dry conditions prevail, Pirelli has made the Ultra Soft, Super Soft and Soft compounds available this weekend
15:54
A few moments ago, Red Bull confirmed that Max Verstappen will remain part of the operation through to 2020 https://www.gpupdate.net/en/f1-news/359973/verstappen-to-stay-with-red-bull-to-2020/
15:54
Thursday was dominated by the news that Fernando Alonso will stay with McLaren for 2018, but that announcement has already been trumped
15:53
15:53
Leclerc will step into Pascal Wehrlein's Sauber for the upcoming 90-minute session, for his second of four planned runs, ahead of a mooted full-time 2018 seat
15:52
Also making an appearance will be Ferrari-backed Formula 2 champion Charles Leclerc
15:52
Hartley was a member of Red Bull's junior programme until 2010, and has since competed for Porsche in the World Endurance Championship
15:51
On the other side of the garage will be Brendon Hartley, who has been drafted in to substitute for Pierre Gasly, the Frenchman competing for the Super Formula title in Japan this weekend
15:50
However, Kvyat won't be in the car this morning; Friday tester Sean Gelael will take his place, for the third of four planned sessions
15:49
Sainz Jr.'s exit has had ramifications at Toro Rosso, which has brought back Daniil Kvyat from the cold
15:48
There are a handful of changes up and down the pit lane - Carlos Sainz Jr. will make his first appearance in Renault colours, in the wake of his move from Toro Rosso
15:47
It's a drizzly, murky start to proceedings at COTA, as 20 drivers get set to begin the action
15:46
However, first up is the opening practice session, which, as usual, is scheduled for 90 minutes
15:46
Lewis Hamilton enters the weekend with a 59-point title advantage over Sebastian Vettel, and could clinch the crown on Sunday
15:44
It's the 17th round of the championship, which takes place at the Circuit of the Americas, near Austin
15:42
Hello and welcome to live text coverage from the opening practice session for the United States Grand Prix!