Conor Murray has emerged as a major doubt for Munster's Champions Cup semi-final against Saracens in Dublin next week.
The scrum-half has not played since injuring his shoulder in the Six Nations defeat to Wales last month and though he was initially named in the team for the quarter-final win over Toulouse he will not face Ulster this weekend.
Neither will ankle injury victim, back-row CJ Stander.
"Conor and CJ, we are tying to get them back, but like last week we are not quite sure if they'll be ready this week," coach Rassie Erasmus told the Irish Independent.
"(Conor) almost came back for the Ireland game and then the next week and then the next week. I must also accept it is something where it just takes time to heal.
"When you get a stinger it does some damage, I think he did more damage initially than everybody thought. I think the shot, the actual stinger he got, did more damage that initially thought there.
“I think CJ has probably got a better chance than Conor, just with the speed of recovery of the two at this stage.
“But then again both of them might be ready or not ready… I have got a gut feeling they have got a good chance I think, but not this week.”
Tyler Bleyendaal and Donnacha Ryan are also serious injury concerns for the province.
