Hamilton fastest, Verstappen 2nd, Vettel 3rd
Vettel spins, complaining of handling problems
Hamilton can win the world title on Sunday
Final practice at 17:00 BST on Saturday; qualifying at 22:00
Fastest so far, top of the championship and with an outstanding record at this race.
Things are certainly looking good for Lewis Hamilton. He has won the last three races held at the Circuit of the Americas.
He also has more podium finishes in the USA than anyone else in the field.
Image source, F1And then Hamilton goes faster with his next lap.
And it is leading to some much better times. Lewis Hamilton was momentarily fastest, before Max Verstappen edges faster.
We expected everyone to come back out on super soft tyres and that is what is happening.
Your first Formula 1 memories / memorable F1 debuts
David O'Reilly: Senna in qualifying at Adelaide 1986. Black and gold Lotus. Car #12, Murray Walker commentating. Sensational.
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Andrew Benson
BBC Sport’s chief F1 writer in Austin
Hydraulic leak for Alonso. He'll not take part in this session.
Ricciardo certainly does improve with a time of 1:40.297. He becomes only the second man out on the super softs and it proves a good decision as he moves quickest, in front of Sebastian Vettel, the other driver to have done a lap on the super softs. Ricciardo nearly five seconds faster than Vettel.
Expect a few more to go out on the super softs shortly.
Image source, Getty ImagesDaniel Ricciardo is the only man out on the track at the moment. He'll be looking to improve as he is only the 10th fastest so far.
Your first Formula 1 memories / memorable F1 debuts
Warind: Lewis' first. Australia 2007. He came third behind Kimi and Alonso. He's won 113 more podiums and three World titles since then.
Kayleigh: First GP was Silverstone 2013. Tyres exploded, Rosberg won, Webber's last F1 race there, I got sunburn. Was a wonderful experience!
David Milner: Mark Webber got a Minardi in a points finish on his debut, in Australia I think. Hope the new Antipodean does as well.
This could be the last weekend that we ever say Nico Rosberg is the reigning Formula 1 world champion.
Is he missing the Formula 1 game? Doesn't look like it, as this week he got to spend some time with the family and ride on a jet ski. Tough life.
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Those standings are not going to change any time soon as everyone is in the pits. All of them. We still have more than 40 minutes left of the practice session.
Image source, Getty ImagesHe may need to "adapt myself to the car", but Carlos Sainz has just gone fifth fastest.
Sebastian Vettel, who moved on to the super softs, has gone fastest with a time of 1:45.960, nearly two seconds faster that Felipe Massa. Max Verstappen third, Stoffel Vandoorne fourth, Sainz fifth, Esteban Ocon sixth, Lance Stroll seventh, Nico Hulkenberg eighth, Lewis Hamilton ninth and Daniel Ricciardo 10th.
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Andrew Benson
BBC Sport’s chief F1 writer in Austin
Carlos Sainz is the other part of the driver swappage this weekend - it is his move to Renault that has precipitated the issue at Toro Rosso. Sainz is up against it jumping into a new car towards the end of the season and taking on Nico Hulkenberg and he is keeping his feet on the ground.
“Let’s wait and see,” he said, when he was asked what his goals were. My main target has to be to go session by session. I’m the first one who wants to be on the pace straight away, but I cannot get too excited about that. I need to cover all the procedures, all the steps that I want to take, little by little, to get to know the car.
"I need to adapt myself to the car and I need to adapt the car to myself at the same time. That takes a bit of time and I’m going to go step by step and hopefully get there as soon as possible.”
This race is also the first for Carlos Sainz in Renault after his mid-season move from the Toro Rosso team.
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Image source, Getty ImagesSpeaking of the Hulk...
Renault's Nico Hulkenberg spoke to BBC Sport earlier this week and opens up about his fear of spiders, how he deals with slow drivers in the fast lane and the one question he hates being asked by journalists.
Nico Hulkenberg: So what does make the Hulk angry?
Nico Hulkenberg has just enjoyed his lap to move up to sixth fastest in his 'Pink Panther', well, sort of.
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BBC Radio 5 live sports extra
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That Sebastian Vettel lap is a good start for him, as he jumps up to second quickest, with Max Verstappen celebrating his new Red Bull contract by being the fastest so far.
Andrew Benson
BBC Sport’s chief F1 writer in Austin
Image source, Getty ImagesOn the other side of the McLaren garage from Fernando Alonso, it is a familiar story for Stoffel Vandoorne. The Belgian has a five-place grid penalty after Honda decided to change his internal combustion engine.
The Japanese company says it has taken what will be his eighth engine - the limit before penalties is four - because it is high mileage, although there are also some performance “tweaks”. So far, Alonso is penalty-free. For this race, at least.