Fabio Quartararo topped the times in Saturday's final practice session ahead of San Marino MotoGP qualifying, pipping Alex Rins with a fastest lap of one minute, 32.197 seconds.
Championship leader Quartararo took the lead in the practice at Misano in his 14th lap, and finished less than a 10th of a second ahead of Alex Rins with Francesco Bagnaia, who topped the morning's third practice session, in third.
France's Yamaha rider Quartararo leads the overall standings from Ducati's Bagnaia, who won his first MotoGP last weekend at Aragon, by 53 points with five races remaining in the season.
In the morning's Moto3 third practice Turkey's Deniz Oncu lost control of his KTM on the bend into the finishing straight and landed heavily on the ground.
The 18-year-old was taken away by ambulance although the medical team said he was conscious, and Oncu re-appeared later smiling with his thumb raised before taking his place with the mechanics to watch the rest of the day's proceedings.
A few minutes after Oncu's crash Honda's Italian rider Alberto Surra clipped the back of Yuki Kunii's bike before coming off and being pinned under his motorbike.
The 17-year-old was conscious as he was taken away for medical tests and will undergo more on Sunday.