Valentino Rossi set the fastest time on the first day of MotoGP testing in 2010 at Sepang.
The reigning world champion completed 54 laps on the 2010-spec Yamaha YZR-M1 and was one of four riders to lap quicker than the circuit's official record.
"Today was very important because this year we have just six days of testing in which to set the bike, so we can not waste any time," said Rossi. "This first day was very positive, we tried the new bike and it is quite fast - Yamaha has worked very well over the winter.
"Now we need to spend time on setting some electronics and other things. This is only the start but it seems we're already in good shape."
Casey Stoner was second fastest for Ducati, half a second slower than Rossi, with Colin Edwards third for Tech 3 Yamaha and Loris Capirossi fourth for Suzuki.
Jorge Lorenzo set his best time on the penultimate of his 57 laps, putting him fifth quickest, ahead of the lead Honda of Andrea Dovizioso, Ducati's Nicky Hayden, the second works Honda of Dani Pedrosa and Mika Kallio's Pramac Ducati.
Hector Barbera was the fastest of this year's MotoGP rookies, setting the 10th quickest time on the Aspar Ducati.
Of the other newcomers, Aleix Espargaro (Pramac Ducati) was 11th, Ben Spies (Tech 3 Yamaha) 12th, Alvaro Bautista (Suzuki) 14th, Marco Simoncelli (Gresini Honda) 15th and Hiroshi Ayoama (Interwetten Honda) 17th.
Pos Rider Bike Time
1. Valentino Rossi Yamaha 2m01.411s
2. Casey Stoner Ducati 2m01.902s
3. Colin Edwards Tech 3 Yamaha 2m01.932s
4. Loris Capirossi Suzuki 2m02.102s
5. Jorge Lorenzo Yamaha 2m02.165s
6. Andrea Dovizioso Honda 2m02.630s
7. Nicky Hayden Ducati 2m02.792s
8. Dani Pedrosa Honda 2m02.866s
9. Mika Kallio Pramac Ducati 2m02.987s
10. Hector Barbera Aspar Ducati 2m03.030s
11. Aleix Espargaro Pramac Ducati 2m03.133s
12. Ben Spies Tech 3 Yamaha 2m03.142s
13. Randy de Puniet LCR Honda 2m03.456s
14. Alvaro Bautista Suzuki 2m03.558s
15. Marco Simoncelli Gresini Honda 2m03.609s
16. Marco Melandri Gresini Honda 2m03.609s
17. Hiroshi Aoyama Interwetten Honda 2m03.651s