Munster and South Africa lock RG Snyman faces another lengthy spell on the sidelines after sustaining a second ACL tear in just over a year.
The 26-year-old World Cup winner was tore his anterior cruciate ligament injured in Munster's victory over Scarlets in Llanelli on Sunday.
Snyman suffered the same injury in August last year.
"We are all hugely disappointed for RG," said Munster coach Johann van Graan on Monday.
The 43-13 win in Wales was the third game of Snyman's comeback with the second row forced off after a tackle midway through the second half.
"After doing everything that was asked of him and working so hard to get back into great shape everyone feels for him right now," added van Graan.
"While this is a setback, we know RG is young and resilient given everything he has gone through in the last year so there is a strong sense of perspective here.
"We have seen what other world class players have done in this position before and they have come back to reach the successful heights of their careers and I would expect no different for someone of RG's class and standing."