Four-time world champion Michael Doohan of Australia rode his Honda to victory in the Malaysian 500cc Grand Prix at Pasir Gudang.

Doohan initially trailed Italian Max Biaggi but took the lead after the 21st of the 30 laps and was never headed. Biaggi finished third behind Carlos Checa of Spain.

"It was a difficult race," said Doohan, referring to the heat which reached 37 Celsius.

Biaggi, who still leads the World Championship because Doohan failed to finish the opening Japanese Grand Prix which the Italian won, said he lost ground on some corners because his "gearbox was too short".

"But I think it was still a good race for me," he said. "I'm looking forward to the next race in Spain."

Tetsuya Harada of Japan rode his Aprilia to a fortunate victory in the 250cc race, beating compatriot Tohru Ukawa by one second. Frenchman Olivier Jacque took third.

Harada and Ukawa trailed Valentino Rossi on his Aprilia during the race but the Italian crashed out at the final turn, allowing Harada to triumph.

There was another Japanese success in the 125cc race courtesy of Noboru Ueda on a Honda.

He beat Italian Mirko Giansati, also on a Honda, by less than half a second. Japan's Tomomi Manako was third, to complete a Honda clean sweep.