Casey Stoner recovered from an early crash to set the pace in MotoGP testing at Mugello in Italy.
The world championship leader was using a new swing arm on his Honda and went down at the San Donato corner during the morning.
But the Australian later recorded a best time of 1m47.326s during the final 15 minutes of running to knock Marco Simoncelli's Gresini bike off the top spot by 0.096sec.
Stoner's Honda teammate Andrea Dovizioso was fastest during the morning, but could not keep pace with Stoner and Simoncelli as the Australian and Italian improved their times by around a second. His third best time overall was over 0.7sec adrift.
Hector Barbera was the best non-Honda rider in fourth on his Aspar Ducati, but was 1.5sec off the pace as he tried out the "step 1" Desmosedici chassis. Karel Abraham – another morning crasher – was next up on his Cardion Ducati, ahead of Honda's Dani Pedrosa, who did not ride after 1pm.
Suzuki rider Alvaro Bautista was seventh, ahead of Randy de Puniet's Pramac Ducati and Hiroshi Aoyama's Gresini Honda.
World Superbike racer Sylvain Guintoli had a tryout for Pramac as a possible replacement for the injured Loris Capirossi and was 10th fastest. He handed his bike over to Moto2 front-runner Andrea Iannone during the afternoon.
The slowest of the 11 riders on-track was another Moto2 rider, Mika Kallio. The regular Marc VDS rider gave the team its MotoGP test debut on a Suter powered by a 1000cc tuned BMW production engine.
Pos Rider Team/Bike Time Gap
1. Casey Stoner Honda 1m47.326s
2. Marco Simoncelli Gresini Honda 1m47.422s + 0.096s
3. Andrea Dovizioso Honda 1m48.061s + 0.735s
4. Hector Barbera Aspar Ducati 1m48.837s + 1.511s
5. Karel Abraham Cardion Ducati 1m48.950s + 1.624s
6. Dani Pedrosa Honda 1m49.015s + 1.689s
7. Alvaro Bautista Suzuki 1m49.199s + 1.873s
8. Randy de Puniet Pramac Ducati 1m49.384s + 2.058s
9. Hiroshi Aoyama Gresini Honda 1m49.423s + 2.097s
10. Sylvain Guintoli Pramac Ducati 1m52.398s + 5.072s
11. Mika Kallio Marc VDS Suter 1m53.668s + 6.342s