PHILLIP ISLAND  - Jorge Lorenzo sealed his second world MotoGP crown after his challenger crashed out, while Casey Stoner claimed his sixth straight Australian Grand Prix at Phillip Island on Sunday.Spain's Lorenzo took the title despite finishing a well-beaten second behind the rampant Stoner, who thrilled his 53,000 home fans by storming to a nine-second victory in his final ride at his favourite track before retirement. Lorenzo's task was made considerably easier when Stoner's Repsol Honda teammate Dani Pedrosa crashed out on the second lap.Lorenzo had led Pedrosa by 23 points going into the penultimate Phillip Island round. He only needed to finish three points higher than his compatriot to secure the championship before the final race in Valencia on November 11. Pedrosa was leading when he high-sided and lost control of his Honda on the right-handed turn four and his race was over in a matter of minutes after the start.The unstoppable Stoner took over to draw away from the field for a convincing win, his 38th in 114 MotoGP starts. "I was quite comfortable to be in second place because Casey was in another world, so I thought I had a great chance to become world champion today," Lorenzo said. "When I was behind Dani he braked too deep and he make a mistake and it was easy for me, but one part of me wanted to ride safe and be world champion and another part of me wanted to try and catch Casey and try to make some pressure on him. But it wasn't like that. He was very fast so I had to finish in second place, which is not bad because I became world champion twice."Lorenzo, who has had to battle the champion Repsol Honda team riders Pedrosa and Stoner on his own with Yamaha, has won six races this season. He heads to Valencia with an insurmountable 43-point lead over the crestfallen Pedrosa. "It's a sad feeling more than disappointment," Pedrosa said. "I pushed as hard as I could and I did what I had to do and I have no regrets for my riding, especially this season. Concerning the crash, it was nothing strange. I just went wider on the corner, I had some chatter and lost the front. Maybe the tyre was not warm enough as well, but it's like it is."Stoner lost all chance of defending the world title he carried off last year at Phillip Island when he missed three rounds after a horror crash at Indianapolis. But he said Sunday's victory was a fitting way to end his troubled season. "That was something extraordinary, it's been a fantastic weekend from the very first lap and otherwise than a little upset (fall) yesterday, the weekend couldn't have gone more smoother," Stoner said."This race has just been amazing for me over the years. This is almost right up there with last year. The crowd was something special and unique. I've seen it quite a few times, not for me, and it was fantastic here in Australia to see so many people out there." Stoner reiterated he would not change his mind about retirement at 27. "There's definitely some aspects of my racing that I'm going to miss for sure, and I have so much respect for Jorge and Dani and we've been challenging and fighting each other for so many years," he said."When I announced my retirement I said that the sport would have to make dramatic changes for me to even consider coming back. I can never say never, but honestly I have no thoughts whatsoever at this time of even thinking of coming back, so nope, sorry." It was a remarkable victory for Stoner, who underwent surgery on torn ligaments and fractures to his ankle, tibia and fibula following a crash during qualifying for the Indianapolis MotoGP in mid-August.The Australian's hopes of defending his world title were ruined by the injury lay-off. Despite his fifth win of the season he is in third spot on the championship standings. Britain's Yamaha rider Cal Crutchlow rounded out Sunday's top three, finishing 14.570 seconds behind Stoner.