Italy's Rossi crowned world champion

Italy's Valentino Rossi sealed his second successive MotoGP world championship on Sunday after finishing third at the Malaysian Grand Prix.

The championship was Rossi's fourth for Yamaha and his seventh premier class world title overall.

Ducati rider Casey Stoner made light of wet conditions at the Sepang circuit in Malaysia, snatching the lead from Dani Pedrosa on the first lap and then powering away from the Spaniard.

Pedrosa finished in second place while Jorge Lorenzo, the only rider who had any hope of catching Rossi in the title race, finished fourth.

Needing only a top four finish to seal the title, Rossi's title hopes were further bolstered when Spaniard Lorenzo was penalised for failing to take his starting position on time and made to start at the back of the grid.

Lorenzo, who had qualified second behind Rossi, battled his way up the order but his efforts came to nothing as Rossi settled after an early error and came home safely to win the title.

"It was a difficult year. This race reflected how the season went -- very tough, with some mistakes, some disappointing results," Rossi told Mediaset television.

"But I won six races, I was consistent and it's another world championship. I thank all the team and everyone who's helped me."

Rossi has an insurmountable 286 points in the world title standings with Lorenzo on 245 and Stoner on 220 with the final race taking place in Valencia, Spain next month.

Honda rider Hiroshi Aoyama earlier celebrated his 28th birthday in style with victory in the 250cc category ahead of second-placed Spaniard Hector Barbera and Italian champion Marco Simoncelli.

Aoyama holds a comfortable 21-point lead over Simoncelli going into the last race in Valencia.

Aprilia rider Julian Simon of Spain, who secured the championship with victory at the Australian Grand Prix last week, held off British team mate Bradley Smith to win the 125cc category. Derbi-riding Spaniard Pol Espargaro took third.