Raul Fernandez set a new lap record to top the standings at the end of a crash-laden practice session at the Indonesian MotoGP on Friday.
The SuperFile-Trackhouse racer clocked 1 min 28.725 sec at a dry Pertamina Mandalika International Circuit to push Aprilia's Marco Bezzecchi, who had led after the first session, into second place by 0.219sec.
Championship leader Jorge Martin, also on Aprilia, came third, with fellow Spaniards Pedro Acosta and reigning champion Marc Marquez behind him.
Fabio di Giannantonio was sixth, followed by Fabio Quartararo, Alex Marquez, Franco Morbidelli and Francesco Bagnaia.
In a second session high on drama, last year's race winner Fermin Aldeguer crashed at the last corner, while Quartararo skidded out at Turn 9, though both were uninjured.
Enea Bastianini, Diogo Moreira, Alex Marquez and Alex Rins also fell. Japan's Ai Ogura crashed earlier, during the first session.
Marc Marquez won in Japan last week to whittle Martin's overall championship lead down to two points with six events of the season remaining.
Going into Sunday's race, Martin sits top with 333 points, with Marquez on 331 and Bezzecchi in third place on 284.