Wales captain Alun Wyn Jones faces a race against time to be fit for the start of next year's Six Nations after he was ruled out for up to 10 weeks with a knee problem.
Ospreys lock Jones, who is test rugby's most capped player and has played 143 internationals, suffered the injury during Wales' Autumn Nations Cup victory over Italy on Dec. 5.
Ospreys coach Toby Booth said Jones is in line to miss up to "double figures" in weeks from when he was injured.
Wales kick off their Six Nations campaign at home to Ireland on Feb. 7 followed by a Murrayfield clash with Scotland six days later.
"We think he'll be double-figure weeks," Booth told reporters. "If I said it to Alun, he'd say: 'I'll be back in eight. That's the nature of the beast.
"He's probably going to be somewhere around that sort of time frame, which is disappointing for him and obviously for us."