Spanish rider Jorge Lorenzo is on target to regain the MotoGP world championship from outgoing titleholder Casey Stoner.

And Lorenzo is poised to claim his second world crown at Stoner's home race, the Australian Grand Prix at Phillip Island next month.

As Stoner is still recuperating after ankle surgery, the title race is now an all-Spanish affair between Lorenzo and Dani Pedrosa.

In his final season of MotoGP, Stoner is hoping to be fit for his farewell race on the island as Lorenzo and Pedrosa chase the title.

Lorenzo is the clear title favourite, according to acclaimed crew chief, South Australian Jeremy Burgess, who helped guide Valentino Rossi to seven world titles.

"The title is now definitely in favour of Jorge but I'm sure it will still be a great battle against Dani," Burgess said.

"With five races to go and Casey Stoner out injured it's between these two guys."

Going into tomorrow's Aragon GP in Spain, Lorenzo leads Pedrosa by 38 points with five races remaining.

If Lorenzo is ahead by 25 points or more after the island GP in four weeks, he'll be declared champion before the final event in Valencia.

Lorenzo extended his margin to 38 points after his win in last week's San Marino GP, in which Pedrosa crashed on the first lap.

But the 2010 world champion is aiming to add to his six wins from 13 races as the title fight heads towards a Phillip Island decider.

Pedrosa has won three races.

"The points gap now is a more realistic reflection of the championship so far," said Lorenzo of his battle against Pedrosa.

"With 38 points I can be a little bit more calm, but it's still not enough. I must push and try to keep winning."

If Lorenzo wins just one of the next four events in Spain, Japan, Malaysia and Australia he is virtually assured of the title.

- AAP