Phil Hughes could be in line for a bizarre Test recall should Shaun Marsh become the latest player ruled out of the tour of South Africa.
There's optimism that Marsh's calf injury isn't serious.
However - given his chequered history - the West Australian has been kept back in Perth for further treatment in case his body doesn't respond in time.
Fast bowler Jackson Bird (back) is another squad member who won't travel with the rest of the squad today. He'll remain in Hobart bowling in the nets.
Australia's injury-free summer has hit a major speed bump, with in-form all-rounder James Faulkner already ruled out with a knee injury, and replaced by Moises Henriques.
Although Faulkner didn't play a Test during Australia's 5-0 Ashes triumph, he had pushed himself to the verge of selection and his knee injury comes as a significant blow to team depth.
Marsh was considered fortunate to get the nod ahead of Hughes in the original squad but, in an ironic twist, the South Australian - with three first-class hundreds this summer - could still make the trip.
George Bailey was the only player dropped from the Ashes squad, but isn't holding his breath for a lifeline - tipping Hughes as the next batsman in line.
"I wouldn't have thought so," Bailey said. "I reckon Phil Hughes would be [called up]."
There would have been a case for slotting Faulkner in as Bailey's replacement for the First Test, and certainly he would have been next man in if something happened to incumbent all-rounder Shane Watson or any of the fast bowlers.
But after starring in Australia's 4-1 ODI series win over England, Faulkner found himself under the knife yesterday, undergoing arthroscopic surgery on his right knee.
Henriques was preferred as a like-for-like replacement, with selectors deciding against subbing Faulkner out for an extra batsman like Hughes or a bowler like Nathan Coulter-Nile.
NSW all-rounder Henriques will vie with Marsh (fitness allowing) and the untested Alex Doolan for the batting vacancy for the First Test starting on February 12.
Australia are confident the sudden wave of fitness concerns won't affect their winning momentum as they prepare to go head-to-head with the world No 1 South Africans.
"It's the No 1 team and a new series. But the positives we've taken out of this summer we'll take with us," said paceman Ryan Harris.
"If we keep playing well, we'll be hard to beat, simple as that. We've got a good feeling and we've just got to keep going winning Test matches and entertaining.
"The guys who come in, they've been in and out of the squad, so they know what it's all about. It's not as if they're new faces - they'll fit in beautifully."
Fellow quick Peter Siddle expects Marsh and Bird to join the squad within a few days - describing the delays to their travel as precautionary. AAP