Red Bull's Max Verstappen topped Friday's opening Formula One practice session for the Bahrain Grand Prix in Malaysia, clocking the fastest time as the four-times world champion eyes his first victory of the season.
The Dutchman lapped the 5.543-km circuit in 1 minute, 37.520 seconds, with Mercedes driver George Russell trailing by 0.383 seconds at the Sepang International Circuit, which is hosting the Bahrain race due to the conflict in the Middle East.
Verstappen's team mate Isack Hadjar claimed third spot, while Ferrari's Charles Leclerc was the only other driver to post a lap time within one second of the Red Bull pacesetter's best effort.
"It's early to get excited because it's only FP1 but Max and Isack did a good job in very difficult conditions - they got into a rhythm pretty quickly," Red Bull team principal Laurent Mekies told Sky Sports F1, according to Reuters.
"Everyone is fighting with the car because of the extreme heat so it doesn't feel good for anyone."
Verstappen won the last Malaysian Grand Prix in 2017 before it dropped off the F1 calendar, with the government saying it could no longer justify the costs.
Friday's session unfolded under sunny skies, though a dusty start-finish straight created hazy viewing conditions in the early stages.
Mercedes, who brought a new upgrade package to their car, arrived sporting a vibrant teal-green livery at the home track of their title sponsor Petronas.
While Russell appeared to adapt quickly to the circuit he was driving on for the first time, championship leader Kimi Antonelli could only manage fifth fastest, more than a second off the pace.
The Mercedes duo, separated by 66 points at the top of the championship standings, both encountered difficulties at turn four, going wide towards the session's end as they grappled with tire wear issues.
They were not alone in their struggles, with Ferrari's Leclerc, who last drove in Sepang in 2017 as a test driver, bluntly summing up the conditions by saying: "The tire degradation is insane."
His team mate Lewis Hamilton, who has one victory in Sepang, was sixth fastest, ahead of Alpine's Pierre Gasly. Racing Bulls drivers Liam Lawson and Arvid Lindblad, and Audi's Nico Hulkenberg completed the top 10.
The FIA said Hadjar, Lindblad and Franco Colapinto exceeded their seasonal allowances for engines and the three drivers received grid penalties.
Racing Bulls confirmed Lindblad was taking a fifth new power unit and would start at the back, while Colapinto received a 10-place grid penalty for exceeding his internal combustion engine allocation for the first time.
Colapinto had already been given a five-place grid penalty for causing the crash at turn one in Baku which took out team mate Gasly and McLaren's reigning champion Lando Norris.
Norris was only 12th fastest, behind his McLaren team mate Oscar Piastri.
