Casey Stoner, who had dominated the Valencia MotoGP weekend only to crash out on the warm-up lap of Sunday's race, underlined what might have been by leading the first day of post-season testing on Monday.

The Ducati star, whose embarrassing exit was officially blamed on cold tyres caused by the team's "grid strategy", dipped 0.118sec under Sunday's fastest race lap.

That had been set by Repsol Honda's Dani Pedrosa, on his way to a victory that cost Stoner third place in the final world championship standings. Stoner was using an audibly different engine with a new firing configuration.

"We tried a new engine configuration designed at improving the rideability of the bike and for the moment it is going really well," said Stoner. "The feedback is more smooth and we improved traction with the same set-up we used over the weekend, so that is positive.

"We also tried some different forks and in general I am satisfied. We didn't do many laps today [32] - just tried to make sure we were working in the right direction. I think we are and I can't wait to get back on track tomorrow, when hopefully it won't be as windy."

Jorge Lorenzo and Fiat Yamaha team-mate Valentino Rossi had a new evolution of the 2010 prototype YZR-M1 to try alongside a 2009 bike. Both gave a positive assessment of the new machine.

Lorenzo, third in Sunday's race, came closest to Stoner - lapping just 0.025sec from the Australian and 0.396sec under his best race lap. Reigning seven time MotoGP champion Rossi set a best lap time 0.166sec from Stoner and a few thousandths under his best race lap.

Pedrosa - who beat Rossi to victory on Sunday - was fourth fastest as he got his first taste of the 2010 RC212V, which features a brand new chassis, swing arm and the latest evolution of the V4 engine.

The Spaniard also got his second chance to evaluate Ohlins suspension. He and team-mate Andrea Dovizioso first tried Ohlins at the Brno test, after which Dovizioso chose to switch to the Swedish brand.

Dani took the new bike and Ohlins equipment to within 0.3sec of his fastest lap in the grand prix and was ranked 0.428sec behind Stoner.

Nicky Hayden - fifth in the grand prix - completed a healthy 58 Monday laps, the best of which was a closer-than-usual 0.698sec behind team-mate Stoner.

"I was really looking forward to getting back out on track today and starting work on next season. We have a direction to work in and loads of work to do but we made a lot of progress already today," explained Hayden. "We don't have a lot of tyres available and just worked with two sets - a hard one and a softer one - with very similar times on both that were not far off my qualifying time from Saturday.

"We tried some engine updates on one of the bikes, some forks and a couple of different settings but this is just the start and it is early to say which is best because the lap times have been very similar. Generally it's been a good first day and I'm happy."

Fresh from his Yamaha MotoGP debut as a wild-card during the race weekend, World Superbike champion Ben Spies completed his first laps as a Tech 3 Yamaha rider on Monday. The American once again underlined his enormous potential with sixth on the timesheets, 0.836sec behind Stoner and 0.519sec faster than his best race lap.

Dovizioso - who, like Pedrosa, rode exclusively with the 2010 Honda - was the first rider outside of one second from Stoner, with MotoGP rookie of the year Mika Kallio (Pramac Ducati) and Randy de Puniet (Honda LCR) eighth and ninth.

After a two-year break, Marco Melandri returned to Honda Gresini to claim tenth on the timesheets. The former Ducati and Hayate rider was 1.179sec from Stoner but a solid 0.624sec under his best ZX-RR race lap.

Of the four 250cc stars making their MotoGP debuts on Monday, Melandri's team-mate Marco Simoncelli made the fastest start. The Italian clocked a 1min 35.229sec to sit just over one second behind the closest regular rider - Suzuki's Loris Capirossi, who tried a new cowling and Akrapovic exhaust - and half a second ahead of Capirossi's rookie team-mate Alvaro Bautista.

Bautista was in turn 0.4sec clear of Hector Barbera (Aspar Ducati), with 2009 250cc world champion Hiroshi Aoyama a cautious 17th and last of the MotoGP riders. Aoyama was still riding in Scot colours for the 'Interwetten Honda MotoGP' team.

A handful of Moto2 machines were also on track, although it seems not all had transponders fitted.

Kenny Noyes (Promoracing) was the fastest of those with an official time, the Spanish Superbike Championship star lapped over a second clear of 250GP regular Ratthapark Wilairot (Stop and Go) with Joan Olive (Promoracing) last of the timed 600c entrants.

In order to allow teams and riders to regroup after the final race of the season, today's MotoGP test began at 1pm and finished at 5pm. A full day of testing takes place on Tuesday, with another half day available on Wednesday.