Ulster and Ireland's Isaac Boss was taken off injured early on in Ulster's Magners League clash with Llanelli at Stradey Park on Saturday evening.
The New Zealand-born scrum-half was seen to be holding his left shoulder as he exited the pitch.
He played in Ireland's Six Nations match against France, which they lost, before being replaced in the first XV by Peter Stringer, who was himself returning from injury.
If he is unavailable for Ireland's upcoming Six Nations games against Scotland and Italy, it is likely he will be replaced on the bench by Eoin Reddan of Wasps.
