Valentino Rossi has put one hand on the 2009 MotoGP World Championship by doubling his advantage over Fiat Yamaha team-mate Jorge Lorenzo to 50 points, after the young Spaniard crashed out of the lead while battling with the reigning six time MotoGP world champion.

Dani Pedrosa's usual fast start saw the Repsol Honda rider take the lead from Rossi into turn one, but the Italian quickly retaliated, while Lorenzo worked his way around Toni Elias for third.

Rossi, Pedrosa and Lorenzo soon pulled away from the field, with Lorenzo - fastest in every track session except qualifying, when he lost out to Rossi by just 0.05sec - then snatching second from Pedrosa at the bottom of the hill on lap 4 of 20.

Pedrosa began dropping away from the M1 riders soon after, leaving Rossi and Lorenzo in a straight one-on-one contest - as the pair punched out lap times over one second faster than any other rider on track.

As the halfway stage came and went, Rossi held a slender 0.2sec advantage over Lorenzo, with best of the rest Pedrosa nearly seven seconds from the lead.

Hopes of breaking Lorenzo early were clearly gone and Rossi instead faced the prospect of another late showdown with the toughest team-mate he has ever had in the premier-class.

But Lorenzo wasn't prepared to wait, and with six laps to go the young Spaniard levered inside Rossi at turn three to take the lead for the first time in the race.

Rossi's response was to try a repeat of Lorenzo's move into turn three next time around; the Italian seemed too far back to actually pass but Lorenzo looked slightly off line and - perhaps distracted by Rossi's presence - lost the front and crashed out of the lead for the second race in succession. The only good news for Lorenzo was that his airbag leathers worked and he escaped injury.

Lorenzo's mistake was similar to that made by Casey Stoner one year ago, and left Rossi to cruise to his fifth race win of the season by almost nine seconds from Pedrosa. The Doctor has also beaten the all time podium record of Giacomo Agostini. Rossi now has a two-race advantage at the top of the championship with just six races to go.