Max Verstappen lapped fastest on Friday in the only practice session for a Qatar Grand Prix weekend set to crown him a triple Formula One world champion.
The weekend is run to a sprint format, with a 100km race on Saturday evening giving the Red Bull driver a first chance to secure the title at the Lusail circuit before Sunday's main event.
Verstappen set a best time of one minute 27.428 seconds, 0.334 quicker than Ferrari's Carlos Sainz, in a session with desert sand blown onto the track by swirling and gusting winds as the sun set.
Ferrari's Charles Leclerc was third fastest with Aston Martin's Fernando Alonso fourth, after being top with four minutes to go, and Red Bull's Sergio Perez fifth.
Perez is the only driver other than Verstappen mathematically in title contention but the Mexican is 177 points adrift with six rounds remaining and a maximum of 180 points to be won.
The session was run in track temperatures of around 38 degrees Celsius whereas qualifying for Sunday's night race will be considerably cooler.
"It’s very warm and then of course it cools down a bit. Whatever you do in FP1 (practice) it’s still not clear for qualifying, it makes it a lot harder and a bit of a gamble," Verstappen told reporters earlier.
"For me it’s a bit of a shame because I think on this track it would be amazing to have a few (sessions) to really set up the car nicely and be fully comfortable going into qualifying for everyone to really get the best out of it."
Saturday is all about the sprint, with a separate 'shoot out' to decide the grid positions for that race.
Mercedes' Lewis Hamilton, the winner when Qatar last hosted a race in 2021, was only 13th in practice this time with team mate George Russell eighth.
