Byrne failed to keep a WRU scheduled doctor's appointment and a subsequent examination organised by his club and hence the delay in diagnosing the problem. The full-back is expected to be out of action for up to five weeks.

Meanwhiile Marty Holah also looks set to miss both games against Munster as he was given a two week suspension for an incident in the match against Edinburgh. He is expected to appeal the decision.

And there will be a change of referee on Sunday with Frenchman Christophe Berdos replacing Dave Pearson who has picked up an injury.

TIckets for Munster's Heineken Cup round 3 game against Ospreys are sold out.