Tomas O'Leary looks will miss the knockout meeting with Leinster next weekend after suffering a fractured ankle while on Magners League duty on Friday night.
Munster's Magners League game against the Scarlets was only seven minutes old when the Irish scrum-half was injured in open play.
With his hands holding his head, the medics treated his left leg as he was carried from the field.
Minutes earlier it hade been the 25-year-old's astute pass that had led to Ian Dowling's first try as Munster maintained their push for the Magners League title. They eventually completed a comfortable 29-10 win to give themselves a cushion at the top of the table.
Munster today (Sat) confirmed that Tomas O'Leary sustained a fractured ankle last night in the course of the Magners League game against The Scarlets at Musgrave Park. O'Leary will have the injury assessed by a specialist today (Sat). Commenting on the injury Munster coach Tony McGahan said, " It goes without saying that we are very disappointed to lose a player of Tomas's stature at this crucial stage of the season, even more particularly so, from his own personal point of view, given that he had just been selected to tour with the Lions, and our thoughts are with him in that regard. "However in immediate terms, in Tomas and Peter Stringer we are fortunate to have two of the best scrumhalves in the country in our squad and the experience of Mike Prendergast to call on when required."
But of more pressing concern for the European champions in the potential absence of their star scrum half. O'Leary has impressed all in the game with his abilities this season, no one more than British & Irish Lions coach Ian McGeechan.
O'Leary was one of three scrum-halves named by McGeechan in his 37-man squad on Tuesday afternoon.
Should he be ruled out of the tour, then Scotland skipper Mike Blair, Wales' 2005 Lions Test No9 Dwayne Peel, England's Danny Care and even O'Leary's Munster team-mate Peter Stringer could come into the reckoning to join Harry Ellis and Mike Phillips in South Africa.
But as far as Munster are concerned, they have a more than adequate replacement waiting in the wings. Double Heineken Cup winner Stringer will step into O'Leary's shoes for next weekends clash with Leinster at Croke Park.
The winner of the all-Ireland semi-final will face either Cardiff Blues or Leicester Tigers in the Heineken Cup final at Murrayfield on May 23.
The directors of ERC voted unanimously at a Board meeting to postpone all decisions including the release of further instalments of ERC's distributable central revenues to the six shareholder countries until 19 February next when the Board will meet again to reconsider the issue.