Leinster flanker Sean O'Brien looks set to miss the start of Ireland's Six Nations campaign.
However, the tightness in his hip has failed to respond to treatment and O'Brien met with a specialist earlier in the week before it was decided going under the knife was the best course of action.
O'Brien will nearly definitely miss the opening two rounds against France and Italy but the break between the visit of Conor O'Shea's side to Dublin and Ireland's trip to Cardiff on 24 March may give the Lion time to recover.
Instead, Leinster have confirmed that the flanker has had a set back in his rehabilitation from the injury and has had to undergo minor surgery, and will definitely miss their final Champions Cup pool games over the next two weeks.
Leinster also revealed that the target is to have O'Brien available again during the Six Nations window, without providing a specific date for his return.
During that period, Leinster have Guinness Pro14 games against Edinburgh, Scarlets and the Kings. The winger has not featured since injuring his knee on Ireland duty in the Autumn Series and will undergo surgery today.
Leinster say a return to play timeline for Byrne, who hasn't played since making his worldwide debut against Argentina in November, will be formalised post-surgery.
Leinster will name their team for the Glasgow game later this afternoon, with Leo Cullen expected to speak to the press with more details about O'Brien's situation.