Dani Pedrosa got the better of team-mate and reigning world champion Casey Stoner, during the first day of post-season testing with next year's 1000cc MotoGP bikes at Valencia.
Pedrosa's best lap was his 40th and last, which put the Spaniard 0.136sec ahead of Stoner's Repsol Honda.
"It's been a good day for testing after so much rain!" said Pedrosa. "The track conditions were good which allowed us to work well on the bike and get the first feeling with the new RCV.
"We made a step forward from August, when I first tried the bike in Brno which is a good thing: we modified the front end a little and I felt the corner entry is better, also under braking. I'm quite satisfied, not because of the lap times but more for the feeling I had. It was a bike test but also a rider test, I feel it's like a schooling for me also and I enjoyed it.
"Not only the bike is new, also the tyres are different for these bikes, the engine is new, you have more power and more torque. We've been riding 800cc quite a long time and I feel that I need to adapt my riding style a little and it's interesting. It's more fun, in general."
Sunday's race winner Stoner, who led the session prior to Pedrosa's late lap, added:
"Everything has gone pretty well for us we're struggling a little bit with the new tyres, we're finding they are giving us a little bit of chatter on the bike. We compared the bike that we tested in Jerez and Brno to the newer version we have here and we found quite a lot of improvements in some small ways with chattering but we still need to work on this some more. In general it was good to be out there on the 1000 and feel the horsepower, it's a lot of fun and I'm looking forward to feeling it on a lot of different tracks!"
Over one-second behind Pedrosa was Yamaha's Ben Spies.
The American took on sole factory testing duties with Jorge Lorenzo unable to ride as he continues to recover from a finger injury.
Spies, who finished Sunday's race in a close second place, put in 73 laps as part of a heavy workload.
Fourth place (+1.358sec) went to an 800cc bike, with Randy de Puniet performing well on a surprise debut with the Rizla Suzuki GSV-R.
Ex-Pramac rider de Puniet is yet to sign, while Suzuki is likewise still to confirm its 2012 intentions. Alvaro Bautista is rumoured to be in discussions with Gresini Honda.
Fifth quickest (+1.466s) was 2011 rookie of the year Cal Crutchlow who, like new Monster Yamaha Tech 3 team-mate Andrea Dovizioso, was getting his first experience of the 1000cc M1.