Valentino Rossi was quickest in practice on the opening day of the Malaysian Grand Prix weekend, ahead of Andrea Dovizioso and Jorge Lorenzo.
At the start of the event that should see his Yamaha team-mate Lorenzo depose him as MotoGP champion, Rossi's late 2m02.724s beat Dovizioso by 0.109 seconds.
Representing the Honda works team alone with Dani Pedrosa still recovering from his Motegi injuries, Dovizioso again showed resurgent form to lead much of the session before Rossi moved ahead.
Lorenzo was third, and only needs a ninth place finish in Sunday's race to claim his first title. He also led the way for a spell in the middle of the hour.
Casey Stoner, chasing a third straight victory for Ducati this weekend, was quickest initially but then lost the front end going into Turn 4 just 12 minutes into the session. He rejoined but could not improve on his early time until the closing minutes, and still remained fourth.
A superb late lap from Alvaro Bautista brought Suzuki's rookie up to fifth, followed by Tech 3 Yamaha's Colin Edwards and Gresini Honda's Marco Melandri - who had a late near-miss with Edwards' team-mate Ben Spies. The latter was ninth quickest, between the impressive Aleix Espargaro (Pramac Ducati) and Randy de Puniet (LCR Honda).
Nicky Hayden struggled again on the second Ducati and was back in 15th, albeit just 1.2s off the pace.
Pos Driver Team Time Gap 1. Valentino Rossi Yamaha 2m02.724s 2. Andrea Dovizioso Honda 2m02.833s + 0.109s 3. Jorge Lorenzo Yamaha 2m02.898s + 0.174s 4. Casey Stoner Ducati 2m03.160s + 0.436s 5. Alvaro Bautista Suzuki 2m03.338s + 0.614s 6. Colin Edwards Tech 3 Yamaha 2m03.393s + 0.669s 7. Marco Melandri Gresini Honda 2m03.438s + 0.714s 8. Aleix Espargaro Pramac Ducati 2m03.471s + 0.747s 9. Ben Spies Tech 3 Yamaha 2m03.477s + 0.753s 10. Randy de Puniet LCR Honda 2m03.539s + 0.815s 11. Marco Simoncelli Gresini Honda 2m03.680s + 0.956s 12. Loris Capirossi Suzuki 2m03.717s + 0.993s 13. Hector Barbera Aspar Ducati 2m03.760s + 1.036s 14. Hiroshi Aoyama Interwetten Honda 2m03.769s + 1.045s 15. Nicky Hayden Ducati 2m03.947s + 1.223s 16. Mika Kallio Pramac Ducati 2m04.023s + 1.299s