The 18th round of the 2023 season marks the beginning of the final run to the end of the campaign, with three grands prix coming up to decide the fate of the championship.
Pramac Ducati’s Martin trails reigning world champion Francesco Bagnaia by 13 points coming to the Sepang round, and kicked off the weekend fastest of all in FP1.
Martin snatched top spot late on with a run on fresh medium rubber to best Marquez, who led for much of the session on his Gresini Ducati.
Bagnaia’s typically low-key approach to Friday mornings in 2023 continued in Malaysia, with the factory Ducati rider 15th.
Aprilia’s Aleix Espargaro kicked off proceedings with the first reference lap of the session at 2m02.066s inside the first five minutes.
Martin took over from Espargaro with a 2m00.984s a few moments later, before Alex Marquez began his stay at the head of the times with a 2m00.680s.
With just over half an hour to go, Marquez improved to a 2m00.530s, which would stand as the benchmark until the closing 10 minutes.
He would be deposed by Yamaha’s Franco Morbidelli, who posted a 2m00.055s on a fresh hard rear tyre.
But a late charge from Martin, who posted a 1m59.513s on a new medium rear, would secure the Spaniard top spot.
Marquez folded in behind with a 1m59.562s at the end of the session, while Johann Zarco completed the top three on the second Pramac Ducati.
Morbidelli headed Yamaha team-mate Fabio Quartararo in fourth, with Luca Marini on the VR46 Ducati sixth from Aleix Espargaro.
Espargaro crashed at the last corner with around 17 minutes to go, with his RS-GP briefly spitting flames from the rear of the bike before the marshals put the fire out.
Marco Bezzecchi was eighth on the second VR46 Ducati, with Tech3 GasGas duo Pol Espargaro and Augusto Fernandez completing the top 10.
Bagnaia was 15th ahead of factory Ducati team-mate Enea Bastianini, while Marc Marquez was 17th on the leading Honda.
Reigning World Superbike champion Alvaro Bautista was 22nd out of 23 riders as he makes a Ducati wildcard appearance.
Marking his first grand prix session since the 2018 Valencia GP, Bautista was 3.003s off the pace, ahead of only LCR Honda substitute Iker Lecuona.