Australian Casey Stoner upstaged former world champion Valentino Rossi to take the first win of his MotoGP career in the Qatar season-opener on Saturday.

The 21-year-old Ducati rider, starting alongside polesetter Rossi, seized the lead at the end of the first lap and smashed the race lap record on his way to becoming the first winner on an 800cc machine.

Despite the Italian twice going past, Stoner used the Ducati's impressive power advantage at the Losail circuit to take the chequered flag with a 2.8 second advantage.

"The team's been working great," said Stoner, who made his MotoGp debut only last year. "We struggled in a few parts of the track during the race where Valentino was a bit quicker but I just used what we had to our advantage.

"I think I did my fastest lap on the last lap so we were there, we had it."

Stoner said the pressure of having Rossi, the greatest rider of his era, breathing down his neck for lap after lap was no different to any other race.

"I had Marco (Melandri) pass me last year in Turkey going into the last couple of corners," said the Australian, who started on pole in Qatar last year.

"It doesn't matter who is behind you, if they are capable of going that quick they are capable of passing you and capable of winning."

Rossi, winner in Qatar for the past two years and starting on pole position on a much-improved Yamaha, said he had done the best he could.

"Compared to first race of the last season, this is a good result. I am happy. There is not much difference between the two bikes (Ducati and Yamaha) but Casey rode a perfect race and I had no chance," said the Italian.

Honda's Spanish title contender Dani Pedrosa won a close battle for third place with Suzuki's American John Hopkins, who injured his hand in pre-season testing and ended the race grimacing with pain after a brave ride.

Pedrosa, aged 21 years and 162 days, became the youngest rider to chalk up 50 grand prix podium finishes.

The Spaniard's team mate and defending champion Nicky Hayden, started ninth and eighth after a brief tussle with Suzuki's Australian Chris Vermuelen.

Three riders crashed out early in the race. Ducati's Loris Capirossi slid off the track in the seventh lap while Honda's veteran Spaniard Carlos Checa and Kawasaki's Randy De Puniet went out in the eighth.

Ilmor, MotoGP's newest team, struggled with Australian Andrew Pitt retiring in the pits and Briton Jeremy McWilliams failing to start after crashing in qualifying.

The race was the first since engine capacity was reduced from 990cc to 800.