Casey Stoner was fastest in both MotoGP practice sessions Friday for Sunday's Australian Grand Prix, the 27-year-old Australian's final home race before he retires.

Aiming for his sixth successive win at Phillip Island and racing just weeks after surgery on his right ankle, Stoner clocked 1 minute, 30.374 seconds in the morning session, faster than world championship contenders Jorge Lorenzo (1:31.279) and Dani Pedrosa (1:31.533).

In the second session, Stoner was the only rider to break the 1 minute, 30-second mark with his fastest lap of 1:29.999.

Honda teammate Pedrosa was second-fastest in 1:30.884 and Lorenzo third on the 4.445-kilometer (2.76-mile) Phillip Island circuit.

"I've been improving every day, but today helped me with some confidence," Stoner said.

"I've got to move on this track a lot less than (his comeback race) in Japan and Malaysia, so I've had a lot less issues with the ankle on the bike."

Lorenzo leads Pedrosa by 23 points in the championship standings and the Spaniards are the only riders who can win the title with two races remaining.

Lorenzo said he won't risk a top-10 finish in Sunday's race in an attempt to clinch the title ahead of Pedrosa, even though he could secure it with the right mix of results at Phillip Island. The final race of 2012 is in Valencia, Spain, on Nov. 11.

"It would be great and we have possibilities (to wrap up the title in Australia), but we're not going to go crazy to make it here," Lorenzo said. "The most important thing is to make it. More than ever we must really concentrate and focus and not make any mistakes."

Qualifying in all three classes, including Moto2 and Moto3, will be held on Saturday ahead of Sunday's races.