Scarlets back row forward Rob McCusker has been called into the Wales 2011 RBS 6 Nations squad to replace Newport Gwent Dragons flanker Toby Faletau, who has withdrawn through injury.
Faletau had a scan on an injured ankle last night which revealed ligament damage ruling him out of action for up to six weeks.
"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."
McCusker has three caps, appearing as a substitute against South Africa at the Millennium Stadium last summer before entering proceedings from the bench for both Tests of the following tour of New Zealand.
He has been a vital part of the rejuvenated Scarlets' Magners League campaign which has seen the West Wales region climb to second place. McCusker has made nine league appearances so far this season.
Meanwhile Faletau has been equally impressive form for the Dragons and has made five appearances, scoring one try in the process.
He could return to the Welsh squad for the final two games of their Championship campaign against Ireland and France and for the Dragons on March 25 against Leinster.