While Wales caretaker coach Rob Howley sweats on the fitness of George North and Scott Williams, Australia have given a vote of confidence to the side that won the first Test 27-19.
North (dead leg) and Williams (facial injuries) are hoping to return to full training on Thursday after the Welsh side has moved on to Melbourne, with Howley describing them as "minor injuries".
Meanwhile, Wallabies coach Robbie Deans is hoping for a clean bill of health for Waratahs tight head prop Sekope Kepu to ensure he can field exactly the same XV.
Kepu strained a tendon in his forearm in Brisbane and will undergo a fitness test before the weekend.
Should he pass, Australia will be unchanged.
Regardless of how North and Williams recover, Wales will not be able to follow Deans' lead.
Number eight Toby Faletau has been ruled out of the tour with a broken bone in his hand, with former captain Ryan Jones primed to step into his shoes having been chosen to lock the scrum against the Brumbies on Tuesday night.
Ospreys lock Ian Evans, who played in every minute of every game in the Six Nations Grand Slam, is included among the replacements for the midweek fixture after arriving in Australia straight from his wedding on Friday.
If he shows no ill effects of jet lag then he could return to the second row in Melbourne.
Australia side for second Test v Wales: A Ashley-Cooper; C Vuna, R Horne, P McCabe, D Ioane; B Barnes, W Genia; B Robinson, T Polata Nau, S Kepu, R Simmons, N Sharpe, S Higginbotham, D Pocock (captain), W Palu. Replacements: S Moore, B Alexander, D Dennis, M Hooper, N White, A Faingaa, M Harris.