Jamie Roberts has emerged as a major fitness doubt for Wales' autumn Tests.
The British and Irish Lions centre faces being sidelined for up to two months after undergoing ankle surgery.
Roberts, who has won 53 caps and scored a try in the Lions' series-clinching third Test victory over Australia this summer, currently plays for French Top 14 club Racing Metro.
RBS 6 Nations champions Wales kick off their autumn campaign against South Africa on November 9, then face Argentina and Tonga before a concluding autumn appointment with Australia on November 30.
Because the Wallabies encounter falls outside the International Rugby Board autumn international window, Racing would be under no obligation to release Roberts for that fixture, even if fit.
"Jamie has reported back to us after 10 days in Cardiff for the operation," Racing assistant coach Laurent Labit said on the www.walesonline.co.uk website.
"He will be out for at least two months after surgery and will hopefully be back playing some time in November, but he will probably miss the Wales Tests."