Australian captain Michael Clarke on Thursday admitted he may not be fit for the first Ashes Test against England next month, with his long-standing back problem needing extended treatment and rest.
Clarke was ruled out of Australia's one-day tour of India in October and while desperate to be ready for the first Ashes Test in Brisbane on November 21, the star batsman is pragmatic.
"Where I sit right now is I don't know when I'll be back playing cricket," he said. "We have no idea how long it's going to take.
"There's certainly no guarantee (for the first Test) at this stage. It's hard for me to say that because I'm trying my best not to look at it like that.
"I'm always positive and if they ask me, I'll say I'll be fit in a week's time. But you ask Alex (Kountouris, team physio) who knows me very well, and he'd say there'd be doubt I won't be right."
Clarke has been plagued by back problems for years and they flared up again before Australia's final ODI in Southampton last month at the end of a gruelling five-Test Ashes tour to England, which Australia lost 3-0.
He played in that game, but selectors were reluctant to take any more risks with him given the big home summer coming up, and ruled him out of the India tour.
Coach Darren Lehmann said all he could do was hope Clarke would be fit to face arch-rivals England.
"I hope he improves his back pretty quickly," Lehmann said.
"(The Ashes) is a long way off so hopefully with all the medicos behind him getting it right he should be right.
"But only time will tell. I can't worry about that. What I can worry about is making sure all the other players are ready to go as well... getting the right side for the first Test match."
Australia are due to play five Tests against England, starting in Brisbane.