Dani Pedrosa set a commanding pace as Honda predictably led the way in opening practice at Sepang.
With Yamaha's Jorge Lorenzo sidelined by the hand injury he sustained at Phillip Island, it was no surprise to see the four works-specification Hondas monopolising the leading positions in Malaysia.
Pedrosa was quickest, dipping under the lap record with his 2m01.916s, as he beat team-mates Casey Stoner and Andrea Dovizioso by 0.6 seconds. Newly-crowned champion Stoner only snatched second from Dovizioso with his last lap of the morning.
Marco Simoncelli completed the top four on Gresini's Honda.
Alvaro Bautista was fastest non-Honda rider in fifth for Suzuki, which is back up to two bikes this weekend with the return of John Hopkins, who started his weekend with 14th place.
Ben Spies was sixth for Yamaha, followed by a late surge to seventh from Pramac Ducati's Randy de Puniet. Colin Edwards (Tech 3 Yamaha) and Hiroshi Aoyama (Gresini) took eighth and ninth, with Valentino Rossi completing the top 10 on the leading factory Ducati.
Lorenzo's stand-in Katsuyuki Nakasuga was 17th, 3.4s off the pace. He had a minor fall at the final corner but was able to get the bike restarted and continue unscathed.
Nakasuga ended the session in front of Aspar Ducati's Hector Barbera, who only completed four laps before going for medical checks as he returned after breaking his collarbone at Motegi.
Pos Rider Team/Bike Time Gap 1. Dani Pedrosa Honda 2m01.916s 2. Casey Stoner Honda 2m02.557s + 0.641s 3. Andrea Dovizioso Honda 2m02.590s + 0.674s 4. Marco Simoncelli Gresini Honda 2m03.311s + 1.395s 5. Alvaro Bautista Suzuki 2m03.558s + 1.642s 6. Ben Spies Yamaha 2m03.586s + 1.670s 7. Randy de Puniet Pramac Ducati 2m03.760s + 1.844s 8. Colin Edwards Tech 3 Yamaha 2m03.778s + 1.862s 9. Hiroshi Aoyama Gresini Honda 2m03.908s + 1.992s 10. Valentino Rossi Ducati 2m04.280s + 2.364s 11. Karel Abraham Cardion Ducati 2m04.345s + 2.429s 12. Nicky Hayden Ducati 2m04.474s + 2.558s 13. Loris Capirossi Pramac Ducati 2m04.521s + 2.605s 14. John Hopkins Suzuki 2m04.609s + 2.693s 15. Cal Crutchlow Tech 3 Yamaha 2m04.666s + 2.750s 16. Toni Elias LCR Honda 2m04.890s + 2.974s 17. Katsuyuki Nakasuga Yamaha 2m05.390s + 3.474s 18. Hector Barbera Aspar Ducati 2m06.199s + 4.283s