Casey Stoner led the way in practice at his home grand prix as the Australian set the fastest time in Friday's second practice at Phillip Island.
The Repsol Honda rider clocked one minute 29.999 seconds, 0.855 seconds clear of team-mate Dani Pedrosa.
The championship leader - Spain's Jorge Lorenzo - was third fastest, 1.006 seconds behind Stoner with Britain's Cal Crutchlow taking fourth place.
Lorenzo can win the title this weekend if he wins the Australian GP.
Stoner, who is is showing the right form to win at Phillip Island for the sixth straight year.
Pedrosa improved steadily throughout Friday's practice sessions. The Spanish rider needs to beat his compatriot Lorenzo on Sunday to extend the title race to the final race in Valencia next month.
Tech 3 Yamaha rider Crutchlow's fourth place, 1.368 seconds behind Stoner, was impressive considering the Briton has been struggling with flu-type symptoms in the build-up.
The Briton finished just ahead of team-mate Andrea Dovizioso, who will be looking to improve if he is to overtake third-placed Stoner in the championship standings.
Phillip Island second practice times:
1 Casey Stoner (Aus) Repsol Honda 1 min 29.999 seconds
2 Dani Pedrosa (Spa) Repsol Honda 1:30.884
3 Jorge Lorenzo (Spa) Yamaha 1:31.005
4 Cal Crutchlow (GB) Tech 3 Yamaha 1:31.367
5 Andrea Dovizioso (Ita) Tech 3 Yamaha 1:31.458
6 Alvaro Bautista (Spa) Gresini Honda 1:31.616
7 Stefan Bradl (Ger) LCR Honda 1:31.702
8 Valentino Rossi (Ita) Ducati 1:32.030
9 Nicky Hayden (US) Ducati 1:32.654
10 Randy De Puniet (Fra) Aspar 1:32.674