Il Nuovo Postiglione - Bezzecchi quickest in opening practice for Thai MotoGP

The Italian Ducati-VR46 rider clocked a lap of 1min 30.492sec at a baking-hot Buriram circuit in a session marred by a fall by Aprilia's Aleix Espargaro.

Spain's Espargaro, who is due to retire at the end of the season, was stretchered off but appeared to be conscious.

Pramac's Martin went into the weekend 20 points clear of Ducati reigning champion Bagnaia in the title race after winning the sprint in Australia last weekend and coming second to Marc Marquez in the grand prix.

With just three rounds left in the season, Italy's Bagnaia has little room for error with another 37 points at stake.

Spaniard Martin, who claimed a clean sweep of pole position, sprint and grand prix victories in Thailand last year, took the early advantage, finishing 0.038sec behind Bezzecchi.

Bagnaia was a further 0.162sec back, ahead of six-time world champion Marquez.

Gresini's Marquez, a two-time winner at Buriram, is third in the title battle and still mathematically in with a chance, but at 79 points adrift his hopes are fading.

His brother Alex Marquez was fifth fastest with Bagnaia's teammate Enea Bastianini sixth.

The second practice session gets under way at 3:00 pm (0800 GMT).

The 10 quickest riders from that go straight through to Saturday's second qualifying session which shapes the first four rows of the grid for the sprint race and Sunday's main event.

This group are joined by the fastest two in Saturday's first qualifying stint.

F.M.Buffo--INP