Ireland back row Sean O'Brien looks likely to miss the Six Nations after the injury he suffered against Ulster was confirmed as a dislocated shoulder.
The injury will need surgery and he has been ruled out for between six and eight weeks, almost certainly ruling him out of the entire tournament, though Leinster forwards coach Jono Gibbes is not completely ruling out the Lions start being available for the latter stages.
"Further prognosis of that is that he (Sean) is going to have to have a surgical repair on the shoulder. The time frame of that has probably moved him outside of six weeks," said Gibbes.
"The time frame to return to play hasn't been set in stone but it is significant enough for surgical intervention which means six to eight weeks minimum.
"It looks like that (he will miss the entire Six Nations), but they are not going to put an absolute line in the sand for him. They are just going to see how it goes."
O'Brien (shoulder) and fellow Leinster star Cian Healy (ankle) will therefore both be missing when the Irish start their Six Nations campaign against Scotland on 2 February.
Gibbes added: "Of course a guy like Sean, it would be nice to have him in the team, but it is just an opportunity for other guys really and that is what we have tried to get going at Leinster in the last couple of years.
"Injuries happen, someone else gets to take their place but the same standard is expected."