Casey Stoner topped the first day of MotoGP winter testing at Valencia as a number of riders came to grips with their new teams and bikes.

The 24-year-old Ducati rider completed 32 laps throughout the day, setting a best time of 1m32.660sec to top the time sheet. Yamaha rider Jorge Lorenzo was Stoner's closest challenger, the Spaniard lapping 0.025 seconds slower and relegating his MotoGP champion teammate Valentino Rossi to third.

Dani Pedrosa, who won the Valencia Grand Prix last weekend, and Nicky Hayden were next up for Honda and Ducati, while World Superbike champion Ben Spies was the best of the newcomers as he went sixth quickest on his first day with the Tech 3 Yamaha squad.

Marco Melandri made his return to Gresini Honda after two seasons away and was 1.4sec quicker than his 2010 teammate Marco Simoncelli, who was testing a MotoGP bike for the first time.

Fellow 250cc aces Alvaro Bautista, Hector Barbera and new world champion Hiroshi Aoyama all became acquainted with their new teams as well. Bautista was 15th quickest for Suzuki with Barbera on an Aspar Ducati and Aoyama riding for Daniel Epp's new Honda team.

As well as the 17 MotoGP machines on track, the Promo-Harris and FTR Moto2 bikes were also in action. The quickest of the Moto2 riders was Kenny Noyes for the Promoracing team. His best time was around 1.7sec off those of the 250cc bikes that the class is replacing next year.

Pos Rider              Bike       Time       Gap     Laps
 1. Casey Stoner       Ducati     1m32.660s            32
 2. Jorge Lorenzo      Yamaha     1m32.685s  +0.025s   45
 3. Valentino Rossi    Yamaha     1m32.826s  +0.166s   37
 4. Dani Pedrosa       Honda      1m33.088s  +0.428s   31
 5. Nicky Hayden       Ducati     1m33.358s  +0.698s   58
 6. Ben Spies          Yamaha     1m33.469s  +0.836s   50
 7. Andrea Dovizioso   Honda      1m33.675s  +1.015s   51
 8. Mika Kallio        Ducati     1m33.726s  +1.066s   52
 9. Randy de Puniet    Honda      1m33.775s  +1.115s   61
10. Marco Melandri     Honda      1m33.839s  +1.179s   59
11. Aleix Espargaro    Ducati     1m33.878s  +1.218s   63
12. Colin Edwards      Yamaha     1m33.929s  +1.269s   35
13. Loris Capirossi    Suzuki     1m34.144s  +1.484s   55
14. Marco Simoncelli   Honda      1m35.229s  +2.569s   51
15. Alvaro Bautista    Suzuki     1m35.772s  +3.112s   52
16. Hector Barbera     Ducati     1m36.204s  +3.544s   63
17. Hiroshi Aoyama     Honda      1m37.964s  +5.304s   40