Casey Stoner showed no sign of the illness that has derailed his season when he upstaged Valentino Rossi and Jorge Lorenzo to secure a hat-trick of home Australian Grand Prix wins.

Stoner, who missed three races with fatigue before posting a podium finish at the Portuguese Grand Prix this month, took the tactical battle by 1.935 seconds over champion Rossi in sunny conditions at the 4.45km Phillip Island circuit.

Rossi's second place moved him closer to retaining the title, as the Italian surged 38 points clear of Lorenzo with two races remaining after the Spaniard crashed out before the first turn.

Champion Marco Simoncelli was earlier awarded victory in the 250cc class after the race was red-flagged when a crash left Italy's Roberto Locatelli stricken on the track.

Spain's Julian Simon won the 125cc race in dramatic fashion, overtaking team mate Bradley Smith on the final lap to wrap up the championship with two races left.