The pain intensified during the night and Stoner, in agreement with the team, decided to return immediately to Australia for further medical checks and to begin treatment.

The early return home means that Stoner will not be able to attend the celebrations for Ducati's World MotoGP title victory this weekend in Bologna, which will nonetheless go ahead as planned.

"It's never much fun when you get injured," said Stoner, "but I'd rather it happened when you've got a couple of months ahead of you to recover. I'm sorry to disappoint all the Ducati fans who have given me their support during the season and who had hoped to see me in Bologna on Sunday, but I am sure they would prefer to see me in perfect form again for the first tests on the Desmosedici next season. I'm sure it'll be a great event for everyone at Ducati, they deserve it. We achieved our aim together and I am so sorry that we can't celebrate it together.

"Unfortunately things are much worse than I thought yesterday after the crash, and this morning we decided that the best thing to do was to go back to Australia as soon as possible for further checks with the doctor who operated my right shoulder a couple of years ago. I'm sure he'll get me back in shape again this time," concluded Casey.

Stoner has been fastest of all during his debut with the 2008 Ducati on Tuesday.