Doug Howlett and Donncha O'Callaghan have both been ruled out of Munster's Heineken Cup semi-final against Clermont.
Howlett has been sidelined by a shoulder injury whilst knee trouble will keep O'Callaghan out of the fixture.
Ireland internationals Peter O'Mahony and Keith Earls are also doubts for Saturday's game but Munster boss Rob Penney has not yet ruled them out of participating.
"Donncha has not recovered from his unfortunate knee injury and is out," said Penney to ERC Rugby.
"There are four or five others who are marginal so we are patchworking together a couple of squads.
"Peter is still suffering from a sore foot - he would probably be the main one - and Keith is 60/40 with his shoulder injury.
"He is taking a little bit of contact and we will see what happens during the week and a call will be made before we travel."