McLaren’s Lando Norris led Ferrari’s Carlos Sainz in a delayed and rain-affected first practice session at the Canadian Grand Prix.
A storm in Montreal before the session led organisers to evacuate spectators from the Ile-Notre Dame for a time and the session started after a 21-minute delay for officials to dry the track.
The times tumbled in a brief period of running on dry-weather slick tyres in the final five minutes.
Norris ended up 0.328 seconds quicker than Sainz, with the second Ferrari of Charles Leclerc third fastest a further 0.543secs adrift.
Leclerc, winner of the Monaco Grand Prix two weeks ago, was on a lap that would have put him fastest at the very end of the session but aborted it because of traffic heading towards the final chicane.
Mercedes driver Lewis Hamilton was fourth fastest, ahead of Red Bull’s Max Verstappen and McLaren’s Oscar Piastri.
Despite the difficult conditions, only one driver crashed.
Sauber’s Zhou Guanyu lost control through Turn Five on a patch of water and broke his front suspension.
Changeable weather is predicted for the rest of the weekend and further rain is expected in the second session, which starts at 22:00 BST.