Championship leader Casey Stoner made the most of the devastating speed of his Ducati to see off the challenge of seven-time world champion Valentino Rossi and win the China Grand Prix on Sunday.

The cool 21-year-old Australian took the lead from Rossi at the beginning of the second lap and his third victory in four MotoGP outings this year was all but assured when the Italian made a mistake and went wide around a corner on lap 16.

Stoner, who now tops the riders' standings with 86 points to Rossi's 71, finished the 22-lap race in 44 minutes, 12.891 seconds, more than three seconds ahead of Rossi's Yamaha.

"It was a very difficult race today with a lot of pressure from Valentino behind," Stoner told reporters. "He made sure I knew he was there all the way through. Then he made a mistake and I was able to hold on. It was another big day for us."

Rossi started from pole and managed to pass Stoner several times on corners before being pegged back on the straights where his bike's lack of top speed was exposed.

"I didn't want to give up and just follow Casey, I wanted to attack him," said the 28-year-old. "I'm happy because this track was always going to be difficult for us and we have 20 points.

"The championship is long and the battle will be hard."

American John Hopkins briefly took second after Rossi's error but still rounded out an impressive weekend by finishing third for Suzuki, his first time on the podium in his 82nd MotoGP start.

"For those last two laps I was just hoping nothing would go wrong," the 23-year-old said. "Now it's done, it's done and I can see many more (podiums) coming."

Last year's winner Dani Pedrosa of Spain won a duel for fourth place with fellow Honda rider Marco Melandri of Italy. Stoner's Italian team mate Loris Capirossi was sixth.

World champion Nicky Hayden's title defence looks in tatters after the American had another hugely disappointing race on his Honda, finishing 12th with only three riders behind him.

Spain's Toni Elias, fourth in the championship at the start of the race, also had a day to forget, crashing out after a wild lunge up the inside on the first corner.

Japanese riders Makoto Tamada and Shinya Nakano also failed to finish after coming together on lap five.

In the 250cc race, world champion Jorge Lorenzo of Spain blew away his rivals for his third victory of the season, while Lukas Pesek took the first victory for a Czech in the 58-year history of the 125cc category.