Munster coach Rob Penney has confirmed that Doug Howlett and Donncha O'Callaghan will miss Saturday's Heineken Cup semi-final against Clermont in Montpellier (5pm).
Howlett has failed to recover from a shoulder injury while O'Callaghan has a knee injury.
There are also doubts about Peter O'Mahony and Keith Earls and a decision regarding both players will be taken later in the week.
James Downey is recovering from a hand injury and is expected to be passed fit for the game.
Stephen Archer was already ruled out with a wrist injury.
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