Valentino Rossi will start the four-week 'autumn break' before the final four rounds of the 2009 MotoGP World Championship with an enlarged 30 point lead after victory in the San Marino Grand Prix at Misano.

Rossi - fastest in every session heading into the race, held just a few kilometres from his home town of Tavullia - slipped to third behind Dani Pedrosa and Toni Elias at turn one, then lost out to Fiat Yamaha team-mate and title rival Jorge Lorenzo at the start of lap 2 of 28.

But Lorenzo became clogged up behind Elias and, having failed to make a quick pass, was re-taken by Rossi at turn one of lap 5. Rossi then made quick work of Elias, but Lorenzo also squeezed past the Gresini Honda rider.

The crucial moment came when Rossi overtook Pedrosa with a neat inside move to lead for the first time on lap 8. While Rossi built an advantage, Lorenzo was stuck behind the Repsol rider, whose factory RC212V was quicker out of the corners and held a near 4km/h top speed advantage over Lorenzo - even with the #99 in his slipstream.

By the time Lorenzo found a way past, on the exit of the hairpin after forcing Pedrosa to brake deep on lap 14, Rossi was 1.4sec clear. Lorenzo initially made a slight gain, but having been informed via his pit board of Lorenzo's pass Rossi upped his pace and was an out-of-reach 2.5sec clear with ten laps to go.

The reigning six time MotoGP champion - riding with a donkey's face painted on top of his helmet, a joke at his own expense for crashing at Indianapolis last Sunday - held that advantage to the line for his sixth victory of the season.

Lorenzo pulled a big wheelie over the line for second, while Rossi's team waited in parc ferme wearing huge donkey ears - which Rossi then wore on the podium in front of his adoring fans.

After being overtaken by the factory M1s, Pedrosa held a safe third place to the finish for his seventh podium of the season, 12.4sec behind Rossi. Pedrosa then ran out of fuel on the slowdown lap. The result has moved Pedrosa up to third in the world championship, ahead of the absent Casey Stoner but 80 points from Rossi.

Team-mate Andrea Dovizioso made good early progress from eighth on the grid, but ran wide moments after taking fourth from Elias on lap 6. The Italian spent the closing stages trying to fend off countryman Loris Capirossi, whom Dovizioso re-passed on the final lap.