MotoGP title hopeful Jorge Martin led the way in the opening premier-class practice session of the Thai Grand Prix weekend at Buriram.
Martin, 27 points behind championship leader Pecco Bagnaia after the brutal disappointments of Mandalika and Phillip Island, spent much of the session in third place in the classification - just 0.011s behind leader Maverick Vinales and just 0.009s behind second-placed Alex Marquez.
But after Aleix Espargaro leapfrogged all three, Martin stuck on a medium rear tyre (which is last year's soft and is, despite the designation, the softest available rear compound this weekend) instead of the hard rear (last year's medium) to assert himself comfortably in the top spot.
His first flying lap of the stint was fastest already, and his second was a 1m30.520s that ensured he would top the session.
Only Martin and Vinales had gone into the 1m30s range by the end, Vinales using a fresh hard rear to lap a quarter of a second off Martin.
Tech3 Gas Gas rider Pol Espargaro took third place late on on a fresh hard rear, while his brother Aleix settled for fourth, ahead of Yamaha's Franco Morbidelli - whose best lap came in the tow of Martin.
Rookie Augusto Fernandez made it two Gas Gas-badged KTM RC16s in the top six (the works KTMs of Jack Miller and Brad Binder were 13th and 14th respectively), with sudden Repsol Honda 2024 favourite Fabio Di Giannantonio in seventh for Gresini Ducati and RNF's Raul Fernandez making it three Aprilias in the top eight.
Di Giannantonio's team-mate Marquez and Bagnaia completing the top 10, the latter continuing a trend of relatively inconspicuous starts to MotoGP weekends, having elected not to run a fresh tyre late on.
The lead Honda was that of LCR rider Takaaki Nakagami in 11th. Nakagami is the sole LCR representative this weekend, with Alex Rins ruled out after withdrawing from Phillip Island with pain - which was followed by a successful surgery to fix a hernia in his still-recovering right leg.
It was mostly an incident-free session, with the only flashpoints of note coming when 12th-placed Fabio Quartararo was mightily displeased after getting Turn 4 wrong on a late push to improve his laptime, and when Binder and Marc Marquez had really shocking practice starts post-session (before both getting a normal one at the second attempt).
There was also a surprisingly robust overtake from Luca Marini on Quartararo during the practice start phase.