Valentino Rossi secured his seventh world MotoGP crown after finishing third in the rain-delayed Malaysian Grand Prix in Sepang.

Rossi, 30, began in pole and only needed a top-four finish, with Yahama team-mate Jorge Lorenzo the only rider able to catch up in the standings.

Australian Casey Stoner won the race on his Ducati ahead of Spaniard Dani Pedrosa (Honda), with Lorenzo fourth.

The final race of the championship is in Valencia in two weeks.

Rossi, on 286 points in the standings ahead of Lorenzo (245) and Stoner (220), said: "It was a difficult year. This race reflected how the season went - very tough, with some mistakes, some disappointing results."

"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."

Italy's Lorenzo trailed Rossi by 38 points ahead of the championship's penultimate race and was forced to start from the back of the grid after being penalised for not taking his starting position on time.

With torrential rain hampering proceedings, the race got under way after a 35-minute delay and Rossi immediately slipped back to fifth on the opening bend with Pedrosa taking full advantage through the puddles.

At the end of the first lap Rossi found himself in 11th spot but used all his experience and nerve to slowly work his way up through the field.

Despite the drying conditions during the 21-lap race, the track remained slippery with Frenchman Randy de Puniet sliding off early on and Andrea Dovizioso losing control of his Honda with seven laps to go when pushing for second spot.

With 14 laps remaining Rossi moved up into fourth spot and cruised to the finish line behind Stoner and Pedrosa amidst wild celebrations trackside which involved a chicken being held up dressed in the Italian's blue and yellow colours.

It is Rossi's fourth title for Yamaha and seventh premier class world title overall.

American Nicky Hayden equalled his second-best result of the season with a fifth-place finish on Sunday, ahead of Chris Vermeulen, Toni Elias, Marco Melandri and Loris Capirossi.

Britain's James Toseland struggled and came 15th.

In the 250cc category, Honda rider Hiroshi Aoyama celebrated turning 28 with victory 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.

Britain's Bradley Smith clinched second place in the 125cc world championship by finishing runner-up in Sunday's race.