World champion Casey Stoner will miss Sunday's Czech Grand Prix after heading home to Australia to undergo surgery on his broken ankle and admitted his title defence is virtually over.
The Honda rider fractured his right ankle in qualifying for last weekend's Indianapolis Grand Prix although he decided to race and finished fourth.
But Stoner told reporters on Thursday that his doctors have advised him to have surgery on his damaged ankle to avoid any permanent injury.
"The plan is to get back to Australia as soon as possible because, after travelling, we have to wait for the inflammation to go down before we can have surgery," said Stoner with just seven rounds left to race.
"I've done about as much damage as I can do down there. My doctor is very honest with things. Normally, he has no problem with getting back out there and me riding on injuries.
"Every piece of advice we have seen has said to get off this foot as soon as possible because if I damaged it again, it could be permanent.
"The plan is to come back maybe a race or two before Phillip Island (in Australia in October) but until we have the surgery we really can't say exactly when we will be able to return.
"We had a good opportunity to get some points back at Indianapolis but this has finished our championship at this point. It's disappointing when you go this far into a championship and put in this much effort.
"We were coming to a point in the season to circuits that suit me better. To have this, especially in my last year, is frustrating. It's a big hit to the heart, that is for sure."
Stoner, who will retire at the end of the season, is third in the world championship standings after 11 races, 39 points behind series leader Jorge Lorenzo.