Wales could be without captain Sam Warburton for their Test match against Australia on November 5 because he needs cheekbone surgery.
The 27-year-old fractured his cheekbone during Cardiff Blues' 13-16 defeat by Leinster on Saturday when he clashed heads with Josh van der Flier.
As a result, Warburton now requires an operation to insert a small plate in his face which will sideline him for up to four weeks.
That means he is in a race to return to fitness in time for Wales' opening Autumn international opener against the Wallabies in Cardiff.
However, Warburton should be available for the following November Tests against Argentina, Japan and South Africa.
"It's disappointing for Sam," said Blues backs coach Matt Sherratt.
"He was getting a run of games and getting into some form, so I'm disappointed for him.
"It's not too serious and as far as the Blues are concerned it's chance for someone else to come in and start some games."
The news will be a blow to Rob Howley, who has taken over the Wales' head coach role to allow Warren Gatland to focus on the British & Irish Lions ahead of next summer's series in New Zealand.
Howley's other back row options, in addition to Warburton, are Ospreys' Dan Lydiate, who has not played yet this season after undergoing surgery on a shoulder in June, while number eight Taulupe Faletau has been sidelined with a knee ligament injury suffered playing for Bath a month ago.