Wales must complete the first three rounds of the Six Nations without Taulupe Faletau after the veteran number eight was ruled out by a calf problem.
Faletau will miss the games against England, France and Scotland with the injury sustained in Cardiff’s 33-22 defeat at Ospreys on January 1.
The 35-year-old, who missed the autumn because of a knee issue, is not expected to be back in action until late February.
“It’s not clear on his return but we’re definitely looking at the middle of the Six Nations,” Cardiff coach Corniel van Zyl said.
Wales are already missing captain Jac Morgan and centre Max Llewellyn for a large chunk of the tournament.
Head coach Steve Tandy names his Six Nations squad on January 20.