Martin wins Thai sprint to cut Bagnaia MotoGP lead to 18 points
Pramac-Ducati rider Martin finished 0.933 seconds clear of South Africa's Brad Binder in second on a KTM, with Italian Luca Marini's Ducati-VR46 third. Bagnaia was seventh.
Martin reached the first corner in the lead and was never headed as Bagnaia suffered a poor start from the second row, dropping back to ninth by the end of the opening lap.
Bagnaia, on the factory Ducati, finally found some pace a third of the way through the 13-lap dash and although he clawed his way back to seventh he could not make any inroads on Marco Bezzecchi, who finished sixth on his Ducati-VR46.
Honda's Marc Marquez crossed the line fourth with Aleix Espargaro's Aprilia in fifth.
"It pretty much went to plan," said Martin, who realised he had to be wary once the flying Binder, who swept through the field from fifth on the grid, overtook Marini on the seventh lap to move up to second.
"I tried to save tyres at the beginning," said Martin. "Then I saw Brad overtook Luca so I said: 'OK, maybe now it's time to go'.
"I pushed the lead out to 1.9 (seconds) then I tried to manage the tyres until the end."
Binder started best of all and overtook Bezzecchi and Espargaro to move up to third by the end of the second lap.
The South African thought he might have challenged for the win had he managed to get past Marini quicker and admitted it was frustrating that it took him half the race to move up to second.
"The plan today was obviously not to come second but to win of course but, second place, we'll take it," said Binder.
"At the beginning I struggled to get past Luca and when I did I had already used the best of my tyres."
The result leaves Bagnaia on 369 points going into Sunday's 26-lap grand prix where he will again start sixth on the grid with pole-sitter Martin now on 351 after picking up 12 for the sprint victory.
Martin began the weekend 27 points behind with four legs of the 20-race season to go though he also started from pole a week ago in Australia before his gamble on a soft rear tyre backfired.
Badly fading rubber allowed him to be overtaken on a dramatic final lap by four riders, including Bagnaia on a factory Ducati.
The tyre blunder came just a week after Martin crashed while leading the Indonesian MotoGP to gift Bagnaia a sixth victory of 2023 and an 18-point lead in a championship duel that looks set to go to the wire.
With 25 points available for the winners of Sunday's MotoGP main race the title battle could tighten further before the riders head to Malaysia in two weeks' time.
After that they go to Qatar, before the season finale in Valencia.
