Italy's Valentino Rossi clinched his second successive MotoGP world championship Sunday, finishing third at the Malaysian Grand Prix after a penalty forced title rival Jorge Lorenzo to start from the back of the grid. Australia's Casey Stoner, riding a Ducati, excelled in 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 for a comfortable win. Pedrosa finished in second place while Lorenzo, the only rider who had any hope of catching Rossi in the title race, finished fourth. 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 his seventh premier class title and his fourth for Yamaha. The victory was also Rossi's ninth motorcycling championship overall including his triumphs in the 125cc category in 1997 and 250cc title in 1999. “It's a great achievement for me,” a beaming Rossi, wearing a T-shirt emblazoned with a chicken and the number nine, said in a televised interview. “And you know I have for all the season great rivals. At the end especially Jorge my teammate stayed very close to me. And we did some great, great fight.” Lorenzo, who crashed out at the first corner of the Australian Grand Prix last week, saw his slim championship hopes fade further even before the race began. Plagued with technical problems during warmup before the rain-delayed race, the Spaniard returned to the pit lane late and was made to start at the back of the grid for failing to take his starting position on time. Rossi, however, looked loathe to take advantage of his teammate's misfortune and the Italian took the first corner too wide and fell back into the middle of the pack. The mistake briefly re-ignited the title race, with Lorenzo passing Rossi and pushing his bike up through the field. But the Italian world champion gradually reeled in Lorenzo before crossing the line with a triumphant ‘wheelie'. “(Jorge's) a great driver so congratulations also to him but we are at the top and now we relax and we try to understand this achievement,” said Rossi. The Italian has an insurmountable 286 points in the world title standings ahead of Lorenzo (245) and Stoner (220) before the final race in Valencia, Spain. Stoner's emphatic win after a podium finish in Portugal earlier this month and victory at his home grand prix last week, continued his spectacular return from a mid-season illness that effectively ruled him out of the championship race. “A big thanks to everyone on my team, everyone that supported me and all the doctors that helped me out. It's been very nice to come back here and get results like this,” the 24-year-old said. 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 teammate Bradley Smith to win the 125cc category. Derbi-riding Spaniard Pol Espargaro took third.