Deposed champion Casey Stoner has revealed he faces a career-saving op in the winter to repair his left wrist.

The 22-year-old Marlboro Ducati rider heads into his home Grand Prix of Australia at Phillip Island this weekend in contrasting mood to 12 months ago.

Stoner won in front of an adoring home crowd last year, days after being crowned champion but this year is fighting to secure second place after watching Valentino Rossi seal his sixth title in Japan. And after learning a broken scaphoid bone in his left wrist, originally damaged in 2003, has never healed properly, Stoner now faces corrective surgery.

He said: "I have to have an operation; if I don't it could be my career over.

"It's disappointing, five years after getting an operation done, it starts to flare up now. But in some ways we're lucky it did show us what the real problem was, so we weren't just ignoring it and finding a bigger problem later on.

"It's better for us to get it fixed at the end of this season. It'll take about three months to come good, but we should have that amount of time before testing starts next year and then we should be a little bit more competitive."

Stoner has been affected by the problem since crashing at Misano at the end of August, with the Australian noticeably slowing in Japan last weekend after setting a lightning pace during the first few laps.

He said: "Pain wise it's fine, it's just a weakness in change of direction and things like that.

"I'm a little bit worried about this weekend, to see how many laps I can do in the race before I start getting tired.

"If I feel comfortable and the bike is working well that should make things easier. So we're going to have to work really hard this weekend to set the bike up as best we can."