Red Bull's Max Verstappen was fastest in first practice at the British Grand Prix ahead of Mercedes' Lewis Hamilton.
Verstappen was 0.474 seconds clear of the world championship leader but used a softer tire than Hamilton, whose team started the weekend as strong favorites.
Racing Point's Lance Stroll was third, ahead of Red Bull's Alexander Albon.
Nico Hulkenberg, a last-minute sub for Sergio Perez after the Mexican contracted coronavirus, was a creditable ninth on his return to F1.
The German, who was 0.588 seconds slower than Stroll, had his position confirmed only minutes before the session started because of the wait to prove he did not have coronavirus.
Perez's positive test emerged on Thursday afternoon, and Racing Point chose Hulkenberg over Mexican Esteban Gutierrez.
Hulkenberg, who was out of F1 after being dropped by Renault last season, was preferred because of his long experience, both in F1 and with the team, having driven for them when they were known as Force India in 2012 and 2014-16.
The session took place under cloudless skies and in soaring temperatures of more than 30C.