Israel Folau and Rob Horne will undergo late fitness tests on Thursday afternoon before Australia coach Michael Cheika selects his starting XV to face Wales on Saturday.
Australia are already without flanker Michael Hooper, who was suspended for a challenge on England's Mike Brown at the weekend, and with Folau and Horne respectively struggling with ankle and shoulder problems the coach chose to delay announcing his team for the fixture at Twickenham that will decide the winner of Pool A.
Ben McCalman and Sean McMahon are in contention to replace Hooper in Australia’s back row, while Kurtley Beale is likely to replace Folau should the full-back be ruled out.
Cheika said: “(Folau’s) been okay. He hasn’t run as yet so he’ll run (on Thursday) but the physios are feeling confident about him playing. You never know until a player goes out on the field. We’ll see how he runs.
“It’s a straight swap if he’s not playing, Kurtley Beale will play, there’s no issue there, we just want to finalise a few things and get our bench organised because I think the finishers in this game are going to be really important.
“I think it’s going to go right down to the wire so I want to make sure our finishers are prepared.
“(Horne) will undergo some testing today, and we’ll make some assessments.”
Like Australia, Wales are among the strongest teams in this year's World Cup and, at England's expense, have secured their place in the tournament's knockout stages from its most competitive pool.
Cheika is familiar with Wales coach Warren Gatland’s methods from the latter’s time as head coach of the British and Irish Lions in 2013, and expects him to select Justin Tipuric alongside captain Sam Warburton in Wales’ back row.
“I wouldn’t be surprised if we met two specialist opensides,” he said. “I think Tipuric is a fantastic player as well, I’ve seen him over many years.
“The balance they have in the back row is very good: (Dan) Lydiate is a very low tackler and they work off his tackling.
“I wouldn’t like to compare the two (England and Wales) like-for-like, it’s nearly impossible.
“(But) what I do think is (Saturday) will be more difficult because of the nature of the contest (to top Pool A) and the tournament.
“Wales have an excellent game with variation, they can switch very nicely between playing a kicking game to a wide game straight away.
“You saw when the Lions came to Australia, they played hard defence in all the lead-up games, and then in the first Test they played a jockey defence.
“(Gatland will) set you up and try to sit you down.”
