Yamaha rider Jorge Lorenzo sealed his second MotoGP title by cruising to a second-place finish at the Australian Grand Prix today after Dani Pedrosa, his only challenger to the title, crashed out of contention on the second lap.

Honda's Pedrosa trailed fellow Spaniard Lorenzo by 23 points entering the race and had hoped to take the title battle to the final round, but his challenge ended when he lost control at the Phillip Island circuit's hairpin turn four.

Lorenzo narrowly avoided the flailing Pedrosa and that was the last of his troubles as he settled into a fuss-free run behind local hero Casey Stoner, who delighted home fans by extending his record to a sixth straight victory Down Under.

After Stoner saluted a roaring gallery on the final straight, Lorenzo pulled a 'wheelie' and shook his fist in triumph as he crossed the line more than nine seconds behind.

The ebullient 25-year-old continued the celebrations in the pit lane, burning his tyres to wrap himself in smoke as jubilant team mates and officials jumped up and down around him.

"I'm really really happy with this championship because only we know how difficult it is to fight with riders like Casey, like Dani and to fight with a factory like Honda. It is very hard," Lorenzo told reporters.

"You must be very consistent, never make a mistake and always try to finish the races and be very focused so today is a very special day."

The 2010 MotoGP champion Lorenzo takes an unassailable 43-point lead in the championship, rendering the final round a victory parade in front of home fans in Valencia.

Briton Cal Crutchlow finished third on another Yamaha, matching his best finish of the season.