Dani Pedrosa dominated the opening free practice session at Misano, ending the afternoon six tenths of a second clear of the field.
The Honda rider, fresh from his third win of the year at Indianapolis last weekend, was at the front for the majority of the session.
Jorge Lorenzo (Yamaha) nosed ahead by 0.076s for a spell, but Pedrosa soon reasserted his authority. Although Lorenzo improved his pace several times after that, it was only ever by a few fractions of a second - and in any case Pedrosa moved well out of reach with two minutes to go when he set a 1m34.772s lap.
Then as the chequered flag fell, his team-mate Andrea Dovizioso came through to take second from Lorenzo by 0.06s and complete a Honda one-two.
Yamaha filled the next four places - Lorenzo leading his factory team-mate Valentino Rossi and Tech 3 pair Colin Edwards and Ben Spies.
It was a tough session for Ducati. Nicky Hayden was outside the top 10 for most of the hour, jumped up to fourth briefly, and ended up seventh, while his team-mate Casey Stoner struggled with the bike and was only eighth.
Gresini Honda's Marco Melandri and Suzuki's Loris Capirossi filled the final top 10 positions, with Hector Barbera in the top five for Aspar Ducati early on but pushed back to 11th in the end.
Pos Rider Team Time Gap 1. Dani Pedrosa Honda 1:34.772 2. Andrea Dovizioso Honda 1:35.384 + 0.612s 3. Jorge Lorenzo Yamaha 1:35.444 + 0.672s 4. Valentino Rossi Yamaha 1:35.539 + 0.767s 5. Colin Edwards Tech 3 Yamaha 1:35.834 + 1.062s 6. Ben Spies Tech 3 Yamaha 1:35.892 + 1.120s 7. Nicky Hayden Ducati 1:36.028 + 1.256s 8. Casey Stoner Ducati 1:36.072 + 1.300s 9. Marco Melandri Gresini Honda 1:36.126 + 1.354s 10. Loris Capirossi Suzuki 1:36.277 + 1.505s 11. Hector Barbera Aspar Ducati 1:36.293 + 1.521s 12. Randy de Puniet LCR Honda 1:36.454 + 1.682s 13. Marco Simoncelli Gresini Honda 1:36.533 + 1.761s 14. Aleix Espargaro Pramac Ducati 1:36.716 + 1.944s 15. Hiroshi Aoyama Interwetten Honda 1:37.001 + 2.229s 16. Mika Kallio Pramac Ducati 1:37.697 + 2.925s 17. Alvaro Bautista Suzuki 1:37.900 + 3.128s