Luke Charteris will miss the forthcoming Six Nations Championship after suffering a knee injury playing for Perpignan on Saturday.
The Wales second-row forward ruptured medial knee ligaments during the Top 14 clash against Montpellier.
Charteris is expected to be out for the rest of this season, effectively ending his hopes of making the British and Irish Lions squad to tour Australia next summer.
Wales interim head coach Rob Howley has already lost fly-half Rhys Priestland and prop Aaron Jarvis from his Six Nations plans.
Priestland suffered a serious Achilles tendon injury in Scarlets' Heineken Cup clash with Exeter earlier this month and he is unlikely to play again this term.
Meanwhile, Ospreys ace Jarvis sustained a knee injury during the early minutes of Wales' defeat against world champions New Zealand last month.
Wales kick off their Six Nations title defence against Ireland in Cardiff on February 2, then face a Paris appointment with France eight days later.