ULSTER powerhouse Nick Williams will be sidelined for eight weeks following a medial ligament injury to his left knee in the 23-6 Heineken Cup victory over Glasgow.
It's another blow for coach Mark Anscombe, who has already had to deal with long-term injuries to skipper Johann Muller (arm), Tommy Bowe (knee), Luke Marshall (hand) and Stephen Ferris (ankle).
There was also a further setback for lock Dan Tuohy, who will miss Saturday's final Pool 4 trip to Castres where Ulster require a first competitive victory on French soil if they want a home draw in the quarter-finals.
New Zealand-born Williams (below) will miss at least five games, with Ulster hoping he will be ready to face Edinburgh in a Pro12 game on March 22, or Leinster the following week, in preparation for the Heineken Cup quarter-final in April.
Plucked from relative obscurity by Anscombe, the No 8 has scored seven tries for Ulster this season.
Better news is that Craig Gilroy and Paddy Jackson are both expected to be fit, although Ireland winger Gilroy is expected to go through a concussion protocol test before he gets the all-clear following a bang to the head.
Jackson turned an ankle, but he is responding well to treatment.
Jared Payne suffered discomfort after the game against Glasgow following a groin problem, but he is also expected to be ready for the trip to France.
Prop forward Adam Macklin is likely to be out a few more weeks after he sustained a knee injury during the Ravens 12-8 defeat by Bristol in the British & Irish Cup.
Skipper Chris Henry says the job in Europe is still only half done.
"It's great that we have qualified but I think the most important thing now is that we have a home quarter. That's everything," said the Ireland flanker.