Jared Payne remains an injury doubt for Ulster ahead of their final Heineken Cup game against Castres on Saturday.
The Kiwi full-back is having ongoing treatment on a groin strain and his fitness will continue to be monitored.
Coach Mark Anscombe has indicated that Paddy Jackson and Craig Gilroy, who suffered injuries against Glasgow, "should be ok" for the clash in France.
Number eight Nick Williams has been ruled out for eight weeks with medial ligament damage to his left knee.
The New Zealander hobbled off in Friday's win over Glasgow and an assessment on Monday revealed the extent of the problem.
Fly-half Jackson sustained an ankle injury in the same game, while wing Gilroy suffered a bang to the head.
Ulster have already secured a place in the knockout stages of the competition but they need to win in France on Saturday to be guaranteed a home quarter-final.
Stephen Ferris, Tommy Bowe, Luke Marshall and Adam D'Arcy will all be out of action over the coming weeks because of injury while Johann Muller and Dan Tuohy are also currently ruled out.
To add to Ulster's lengthy injury list, prop Adam Macklin damaged his knee while playing for the Ravens at the weekend and his fitness will be monitored over the coming days.
Ulster lead Pool Four by five points with Northampton second and Castres a further point back and coach Mark Anscombe is determined to secure a quarter-final at Ravenhill.
"We set out as a goal this year to get a home quarter-final, so we are certainly not resting on it," said Anscombe.
"We want to reward our fans with a home quarter-final, so if we don't do that we will let ourselves and our supporters down a little bit.
"Like many French teams they have a home team and an away team. I think they have only lost one game at home this year.
"We know from what we have seen of them this year and playing them earlier in the first round, that they are a formidable forward pack.
"We know where our work is going to be next week and if we don't front up there it is going to be a long day."