Marc Marquez fended off Dani Pedrosa and Jorge Lorenzo to set the pace in MotoGP's opening practice session at Misano.
The Spaniard hit the front early on and was never displaced as he improved several times to eventually end the session on a 1m34.476s.
Pedrosa fought back from early brake issues to jump the two works Yamahas and settle into second, just over two tenths down on his championship-leading team-mate.
Lorenzo, who ended Marquez's string of wins last time out at Silverstone, eventually claimed third ahead of team-mate Valentino Rossi, the pair trading blows several times during the session.
Both men were half a second off Marquez's time, in what was an encouraging first competitive run-out for Yamaha's new seamless gearbox.
Alvaro Bautista and Stefan Bradl made it four Hondas in the top six, while Nicky Hayden beat works Ducati stable-mate Andrea Dovizioso to seventh. The American was the last man to get within one second of Marquez.
Pramac's stand-in rider Michelle Pirro claimed ninth, with Aspar CRT man Aleix Espargaro rounding out the top 10.
It was a disappointing session for Yamaha's satellite Tech 3 squad.
On the back of a horrible home round, Cal Crutchlow struggled with rear balance and was only 11th fastest, two places ahead of team-mate Bradley Smith.
Pos Rider Team Time Laps
1. Marc Marquez Honda 1m34.476s 21
2. Dani Pedrosa Honda 1m34.698s +0.222s 18
3. Jorge Lorenzo Yamaha 1m34.902s +0.426s 19
4. Valentino Rossi Yamaha 1m34.978s +0.502s 22
5. Alvaro Bautista Gresini Honda 1m35.269s +0.793s 21
6. Stefan Bradl LCR Honda 1m35.299s +0.823s 22
7. Nicky Hayden Ducati 1m35.392s +0.916s 20
8. Andrea Dovizioso Ducati 1m35.504s +1.028s 17
9. Michele Pirro Pramac Ducati 1m35.725s +1.249s 19
10. Aleix Espargaro Aspar Aprilia 1m35.800s +1.324s 17
11. Cal Crutchlow Tech 3 Yamaha 1m35.913s +1.437s 17
12. Hector Barbera Avintia FTR-Kawasaki 1m36.198s +1.722s 20
13. Bradley Smith Tech 3 Yamaha 1m36.198s +1.722s 20
14. Colin Edwards Forward FTR-Kawasaki 1m36.652s +2.176s 20
15. Hiroshi Aoyama Avintia FTR-Kawasaki 1m36.661s +2.185s 20
16. Randy de Puniet Aspar Aprilia 1m36.764s +2.288s 20
17. Andrea Iannone Pramac Ducati 1m36.839s +2.363s 20
18. Danilo Petrucci Ioda-Suter-BMW 1m36.943s +2.467s 23
19. Claudio Corti Forward FTR-Kawasaki 1m37.252s +2.776s 21
20. Yonny Hernandez PBM Aprilia 1m37.329s +2.853s 17
21. Karel Abraham Cardion Ducati 1m37.688s +3.212s 17
22. Michael Laverty PBM-Aprilia 1m38.872s +4.396s 18
23. Bryan Staring Gresini FTR-Honda 1m39.024s +4.548s 21
24. Lukas Pesek Ioda-Suter-BMW 1m39.705s +5.229s 17