Australia's Peter Siddle will miss the third and deciding Test against the West Indies because of a hamstring injury.
The fast bowler had been a doubt for the trip to Perth since the completion of the second Test in Adelaide early last week, where he picked up a hamstring strain.
Siddle had declared himself fit to play but team physiotherapist Alex Kountouris revealed on Tuesday the player had woken feeling sore with a back-related hamstring injury.
Fellow Victorian quick Clinton McKay is therefore poised for a Test debut at the WACA and could also play in the first two Tests against Pakistan, the first of which starts at the MCG on Boxing Day.
A second spinner is also likely to be rushed to Perth as cover for off-spinner Nathan Hauritz, who badly injured a finger in training.
He is expected to prove his fitness for the match, however, as the injury is causing him discomfort but not affecting his bowling.
An announcement on a replacement spinner is expected later on Tuesday with either Jason Krejza or Bryce McGain being the likely contenders.
When asked about the fitness of Shane Watson, meanwhile, Kountouris was adamant the all-rounder would play despite his moving gingerly at training in recent days.
The West Indies, who trail 1-0 in the series, have injury concerns of their own, with veteran batsman Shivnarine Chanderpaul and opener Adrian Barath both rated only a 50-50 chance to play because of finger and hamstring problems respectively.
A decision on the two key batsmen will be made on Wednesday morning before the start of play.
