Australia's chairman of selectors John Inverarity has rated captain Michael Clarke a '50-50 chance' of playing in the Boxing Day Test.
Clarke trained separately from the rest of the Australian cricket team during a session at the MCG on Sunday as he continues his quest to be fit for the second Test against Sri Lanka.
Australia's Test captain injured his hamstring during the first Test win in Hobart and Inverarity remains doubtful Clarke will be ready to play the second match of the series at the MCG.
"Look, he's travelling optimistically and well, but he's 50-50 as to whether he'll be fit enough to play on Boxing Day," Inverarity said.
Iverarity added he would be loath to risk exacerbating Clarke's injury by limiting his recovery time.
"He's a very precious asset and I would go low risk," Inverarity said.
"He's always upbeat, he desperately wants to play, but we certainly don't want to push him especially hard in a Test and for him to break down."
Shane Watson will take over Clarke's duties as captain if the latter fails to recover for the second Test but has not started to think about it yet.
Watson is convinced his skipper could still prove his fitness.
"In the end I know Michael will be doing everything he possibly can to be able to get right for this Test match and everyone's got their fingers crossed that he'll be right but if the opportunity does arise (to be captain) then I'll re-focus then," Watson said.