Irish flanker Sean O'Brien set to miss Six Nations
Leinster flanker Sean O'Brien is likely to miss Ireland's Six Nations campaign after it was confirmed he will need surgery for a dislocated shoulder.
The Lions forward sustained the injury in Saturday's 19-6 win over Ulster.
Leinster forwards coach Jono Gibbs said O'Brien would be sidelined for at least six to eight weeks but the club later extended this to several months.
That would rule O'Brien out of all five matches, the last coming against France on 15 March.
O'Brien, 26, was forced to leave the field after 53 minutes of his side's Pro12 win over their Irish rivals.
The shoulder problem is the latest in a series of injury setbacks for O'Brien, who was making only his second league appearance of the season at the RDS on Saturday night.
The Leinster man is understood to be a target for a number of French Top 14 clubs, along with his provincial team-mate Jamie Heaslip, who is being courted by Montpellier and Toulon.
Another Leinster player, prop Cian Healy, is doubtful for the start of Ireland's Six Nations campaign, after undergoing surgery on an ankle injury.