Casey Stoner won his sixth successive Australian Grand Prix in his final home MotoGP race before retiring, while Jorge Lorenzo clinched the world championship with a second-place finish Sunday at Phillip Island.
Dani Pedrosa, the only rider who could have caught fellow Spaniard Lorenzo for the 2012 series title, crashed out of the 27-lap race while leading on the second lap, sliding out of control in a corner.
Lorenzo, who also won the world title in 2010, held a 23-point championship lead going into Sunday's race and needed only three points to clinch the title.
Britain's Cal Crutchlow was third Sunday on the 2.76-mile circuit.
Starting from pole, Honda rider Stoner was beaten off the start line by both Lorenzo and Pedrosa, with Pedrosa taking the lead from his fellow Spaniard late on the opening lap.
But Pedrosa slid out of control while taking a corner less than a minute later. He returned to the pits, and retired from the race.
For Stoner, who will retire at the age of 27 at the end of the season, it was a remarkable result in front of a record Phillip Island MotoGP attendance of more than 53,000.
Once he inherited the lead from the fallen Pedrosa, Stoner built his lead on every lap - Lorenzo perhaps content to do what he needed to in order to wrap up the title. Stoner eventually beat Lorenzo by more than nine seconds.
Stoner had been dominant all weekend at Phillip Island, having timed a second quicker than his rivals for most of the practice and qualifying sessions, despite his recovery from right ankle surgery a month ago.
He was adamant he would complete the season at Valencia, Spain in two weeks.
"I'm here to finish this season, not just finish my home Grand Prix,'' Stoner said.
"It's not like that for me. I wasn't just planning for this race alone (from his injury). I was planning to come back for as many races as I could before the end of the season.
"But at the same time, I'm not finishing here. I'm going to Valencia to see if I can get another good result.''
Stoner also downplayed any thoughts that he may reconsider his decision to retire.
"I've got no thoughts whatsoever at this time of ever even thinking of coming back,'' Stoner said.
"I'm very established where I'm going (into retirement). I'm not changing my mind every couple of minutes.''
Pol Espargaro of Spain won the Moto2 race, with Australian Anthony West second and new world champion Marc Marquez of Spain third. Marquez's finish gave him 299 points, 33 ahead of Espargaro with just one race remaining in Valencia, Spain in two weeks and 25 points awarded for a win.
Sandro Cortese of Germany took the Moto3 race with Portugal's Miguel Oliveira second and 17-year-old local rider Arthur Sissis of Australia third, the Australian's first podium finish.
Cortese, who clinched the 2012 series title at the most-recent race in Malaysia, led most of the race on his KTM after starting from pole position. Oliveira made a late-race pass on Cortese, but the German recovered to re-take the lead on the second-last lap.