Charles Leclerc topped the timesheets during the second practice session at the United Grand Prix on Friday, as Ferrari continued to show promising signs with its new upgrades.
The Monégasque topped both of Friday's sessions at the Circuit of the Americas, ending the day 0.042 seconds clear of title leader Kimi Antonelli.
Max Verstappen, bidding for three successive wins this weekend, after success in Malaysia and Singapore, was third fastest for Red Bull and just under two tenths off the leader's pace.
Antonelli could be crowned F1 world champion in Austin and become the youngest driver to do so. He would need to take victory for Sunday's race, for George Russell to be ninth or lower and Lewis Hamilton to finish fifth or lower.
Leclerc's teammate Hamilton ended the session down in fourth, with Russell behind in fifth.
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Russell was involved in a flashpoint early in the weekend's second running as he was noted for forcing Leclerc off the track but the stewards took no further action.
McLaren pair Lando Norris and Oscar Piastri were over a second off the pace in seventh and eighth.
This is the first time since 2022 that there hasn't been a sprint race in Austin. Final practice for the United States Grand Prix will get under way at 6.30 p.m. BST / 1.30 p.m. ET on Saturday.
Information from the Press Association contributed to this report.