Wales coach Warren Gatland has called up Scarlets back row forward Rob McCusker to his squad for the RBS Six Nations.
McCusker, who has won three caps off the bench, replaces the injured Toby Faletau.
Dragons flanker Faletau was been forced to withdraw from the squad after a scan revealed he faces six weeks out with damaged ligaments in his ankle.
"Toby has ligament damage to his ankle and will be in a boot for a period of two to three weeks," said Wales physiotherapist Mark Davies.
"He will then begin rehab meaning he is ruled out for around six weeks."