Marco Bezzecchi set a new track record to finish fastest ahead of defending world champion Marc Marquez in practice for the season-opening Thailand MotoGP on Friday.
Aprilia's Bezzecchi roared round the Buriram course in 1 min 28.526 sec to top the timesheets, 0.421 sec in front of Ducati's second-placed Marquez.
Marquez is launching his bid for a record-equalling eighth world title this weekend after dominating the competition last season.
But Bezzecchi proved he will be a force to be reckoned with in a practice session that somehow stayed mostly dry despite ominous dark clouds and rumbles of thunder.
The Italian came through at the end of the session to update his own track record, which he set in pre-season testing last week.
He was also fastest in the morning's free practice.
VR46's Fabio Di Giannantonio was third-fastest in the afternoon session, followed by KTM's Pedro Acosta, Aprilia's Jorge Martin and Gresini's Alex Marquez.
Ducati's Francesco Bagnaia, the 2022 and 2023 world champion, finished 15th, forcing him into Saturday's first qualifying session.
His teammate Marc Marquez was also struggling until he surged up the timesheets with around 20 minutes of the session to go.
The Spaniard begins the season still suffering the effect of a shoulder injury that forced him to miss the final four races of last season.
He said on Thursday that the injury had forced him to change his riding style until he returns to full fitness.
Turkey's Toprak Razgatlioglu, a three-time Superbike world champion making his MotoGP debut, finished the practice session 21st out of 22.
Martin, whose defence of his title last season was wrecked by injuries, crashed 10 minutes into the morning free practice session.
Trackhouse's Ai Ogura also came off in the afternoon session.
The top 10 fastest riders in practice book their tickets for Saturday's second qualifying session, which shapes the first four rows of the grid.
This group are then joined by the two fastest riders from the first qualifying session.
Qualifying determines the grid for both the sprint race on Saturday and the main event GP on Sunday afternoon.