Red Bull’s Max Verstappen headed Ferrari’s Charles Leclerc and Mercedes’ Lewis Hamilton in first practice at the US Grand Prix.
The world champion was 0.156 seconds clear of Leclerc, with Hamilton 0.281s off in his upgraded car.
Red Bull’s Sergio Perez was fourth ahead of Haas’ Kevin Magnussen and the second Mercedes of George Russell.
Lando Norris ended the session 15th, his McLaren team choosing not to do a run on the fastest soft tyre.
Norris’ team-mate Oscar Piastri had a scary moment when he ran wide at Turn Nine and fought a massive movement, with the car snapping left and right and back again before he finally brought it under control. He ended up 19th, after returning to the pits for repairs to his floor.
The session, the only practice before qualifying later on Friday on this sprint weekend, was held in high temperatures of more than 34C, on what is expected to be the hottest F1 race since Austin, Texas, made its debut on the calendar in 2012.
A number of teams have significant upgrades on their cars, most relevantly Mercedes, who have a new floor they hope will point them in the right direction for next year.
Hamilton described the development as “our last big update, or the biggest of the large updates through the season… and hopefully this really kind of tips the needle a little bit and helps us in the right direction of where we want to pursue next year”.
The first signs were promising. Hamilton set the fastest times of all in the first and second sectors of his lap, before fading a little in the final few corners.
Mercedes team principal Toto Wolff said: “On Lewis’ side, the lap times are promising but not like the car was suddenly super-fast. There were some areas the car was more comfortable but George on his side wasn’t satisfied with the way the car was going for him.”
Aston Martin, Haas and Alpha Tauri are the other teams with major upgrades – Aston Martin with a new floor edge, Haas a complete revamp of aerodynamic philosophy and Alpha Tauri the latest in a series of developments aimed at upping their performance.
Daniel Ricciardo is back in the Alpha Tauri after missing five races with a broken hand and he and team-mate Yuki Tsunoda were closely matched in 14th and 13th.
However, it was a troubled session for Aston Martin. Lance Stroll missed most of it with an overheating problem around his left front wheel.
This caused the team to call in Fernando Alonso for his car to be checked. The Spaniard was later sent out and was running fourth-fastest before dropping down to 18th when the other teams put on soft tyres at the end.
Behind Russell, Williams driver Alex Albon impressed with the seventh-fastest time, ahead of Ferrari’s Carlos Sainz, Haas driver Nico Hulkenberg and Pierre Gasly’s Alpine.
Qualifying, which sets the grid for Sunday’s grand prix, is at 22:00 UK time (16:00 local).
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