Garry Ringrose is to miss the start of Ireland's Six Nations campaign.
Leinster have confirmed the centre will not be fit to play in their final two Champions Cup pool matches after suffering an ankle injury in Saturday's Pro 14 victory over Ulster.
With an estimated recovery period of five to six weeks, it means he will almost certainly miss Ireland's opening two Six Nations games with France and Italy.
On a positive note for Leinster, Tadhg Furlong remains in contention for Sunday's visit of Glasgow as he's making good progress through the return-to-play protocols.
Leinster coach Stuart Lancaster said that losing Ringrose is a blow for all concerned.
"I'm disappointed for the team, but disappointed for Gary in particular, because I know how hard he worked to get back fit," he said.
He added: "He played his best game, I think, in the Ulster game, but it's one of those injuries that it's uncontrollable really in a sport like rugby.
"He's pretty philosophical about it, so he'll be back in a few weeks, and we'll go from there."