Leinster have confirmed that hooker Richardt Strauss' season is over after he had an operation on a hamstring injury on Monday.
Strauss, who spent a large part of the season on the sidelines with a heart complaint, sustained the injury in Saturday's 15-13 victory over Edinburgh at the RDS.
The Ireland number two is expected to be "out of action for a number of months" due to the injury.
Meanwhile, Ireland back-row Sean O'Brien came through Saturday's game against Edinburgh unscathed and has trained well this week reporting no issue. He had been out of the game for more than five months having injured his shoulder against Ulster at the RDS in December.
Another player back from a knee injury, utility back Fergus McFadden, has also trained well this week and is available for selection for this weekend's semi-final with Ulster.
Elsewhere, scrum-half Eoin Reddan continues to make slow but steady progress from his shoulder injury but a final decision on his availability will not be made until later in the week, while second-row Mike McCarthy's injury is not as bad as first thought he is unlikely to feature this weekend.
Similarly utility back Luke Fitzgerald will not be available for selection.