Connacht centre Robbie Henshaw is fighting to be fit for the Six Nations opener against Italy, but Ulster paid Paddy Jackson and Stuart Olding have been ruled out.
Joe Schmidt will be sweating on the availability of the 21 year-old Athlone native who played at both 12 and 13 during the Autumn internationals after an ankle injury suffered during the Challenge Cup defeat to the Exeter Chiefs last weekend.
Henshaw survived the full 80 minutes after picking up the injury when he was cleaned out of a ruck after five minutes and head coach Pat Lam admitted post-match the injury was a "real concern". Connacht today confirmed that the midfielder sustained a low-grade ankle sprain during the game and has been ruled out of the trip to La Rochelle on Saturday with a place in the quarter-finals up for grabs.
Schmidt will have to plan without out-half Jackson and utility back Olding after both players sustained elbow injuries in the heavy Champions Cup defeat away to Toulon at the weekend and will require surgery.
23 year-old out-half Jackson has an "unstable join" while Olding has ligament damage and both are expected to be sidelined for up to 12 weeks which will be the final fixture of the competition when Ireland travel to Scotland.
Jackson has won 13 caps for Ireland since making his international bow two years ago while Olding has nine caps to his name.