Mason Grady has been ruled out of Wales' remaining autumn games and is a doubt for the start of the 2025 Six Nations, against France in Paris on Friday, 31 January.
The versatile threequarter left the field after suffering ankle damage in the early stages of Wales' defeat by Fiji last Sunday and will undergo surgery.
The 22-year-old's injury is also a blow for Cardiff whose European Challenge Cup campaign begins in December with United Rugby Championship Welsh derbies to look forward to in the festive period.
Fly-half Sam Costelow replaced Grady out of position on the wing in the 17th minute against Fiji, with Wales coach Warren Gatland later saying scrum-half Ellis Bevan should instead have replaced his Cardiff team-mate.
Blair Murray, Rio Dyer, Josh Hathaway and Tom Rogers are the wings vying for starting spots against Australia in Cardiff on Sunday, 17 November.
Forwards: Nicky Smith, Gareth Thomas, Kemsley Mathias, Ryan Elias, Dewi Lake, Evan Lloyd, Henry Thomas, Keiron Assiratti, Archie Griffin, Freddie Thomas, Christ Tshiunza, Ben Carter, Will Rowlands, Adam Beard, Taine Plumtree, James Botham, Jac Morgan, Tommy Reffell, Aaron Wainwright.
Backs: Tomos Williams, Rhodri Williams, Ellis Bevan, Sam Costelow, Gareth Anscombe, Ben Thomas, Nick Tompkins, Max Llewellyn, Eddie James, Owen Watkin, Blair Murray, Rio Dyer, Josh Hathaway, Tom Rogers, Cameron Winnett.