Top 10: Norris, Hulkenberg, Piastri, Alonso, Verstappen, Albon, Russell, Hamilton, Hadjar and Bearman.
Hulkenberg goes second in the Sauber - where did that come from?
Piastri improves and slots into second, 0.2s down on his teammate.
Norris goes 0.3s clear of Alonso to set the fastest time of the session.
He comes into the pit lane after reporting an "oil smell". He's down in 14th.
He pips Verstappen by 0.009s.
A 1m33.648s for Verstappen, 0.8s ahead of Tsunoda.
Russell sets a 1m34.675s on the mediums, a tenth ahead of Hamilton's hard tyre lap from earlier.
Hamilton, Norris, Verstappen, Russell, Piastri, Tsunoda, Sainz, Lawson and Leclerc and Hulkenberg.
Ferrari have opted to run on the mediums for their qualifying simulation. All teams must run on the mediums in SQ1 and SQ2 in sprint qualifying.
Tsunoda and Albon take to the track on softs. 11 minutes on the clock in FP1.
📻 "The brake stayed at 100% all the way!" 😱
— Formula 1 (@F1) October 17, 2025
A very strange lock-up for Esteban Ocon at the Turn 11 hairpin, but he manages to get back to the garage 👀#F1#USGPpic.twitter.com/Z2HzNMUohj
All drivers have set their times on the hard tyre. Expect to see some qualifying simulations in the next 10 minutes.
Hamilton remains on top ahead of Norris, Verstappen, Russell and Piastri.
He slots into second, 0.5s off Hamilton's impressive time from earlier.
Williams say: "Carlos has experienced a problem with his gearbox which we are investigating. He will not join the remainder of FP1 but will ready for Sprint qualifying this afternoon."
Verstappen is on a race run, setting a 1m34.857s.
The debris has been cleared and first practice is back underway in Austin.
Hamilton, Verstappen, Russell, Tsunoda, Norris, Sainz, Lawson, Leclerc, Hulkenberg and Antonelli.
Debris on track that has come off Stroll's Aston Martin.
RB told Hadjar:"Bottas 2 pushing. Bottas now, and then Leclerc 8 seconds."
Hadjar replied: "Yeah mate, stop with Bottas mate. There is no Bottas on track."
Hamilton goes 0.5s clear of Verstappen with another strong lap.
He splits the two Red Bulls to go second, slotting a tenth behind Verstappen.
Verstappen storms to the top of the order with a 1m35.426s, 0.3s ahead of Tsunoda. Sainz completes the top three.
Norris, Sainz, Verstappen, Hamilton, Albon, Tsunoda, Lawson, Russell, Leclerc and Stroll.