Ulster have revealed that Ireland flanker Stephen Ferris will miss the rest of the season after having a second operation on an ankle problem.
The 27-year-old underwent further surgery on Wednesday, during which fragments of bone were removed.
Ferris has been out of action since early November and first had an operation on the ankle in December.
Ulster said he will be out of action for a further three months, effectively ruling him out of Lions selection.
His injury is a major blow for Ulster, who had been hoping to have him back for the Heineken Cup quarter-final against Saracens at Twickenham on 6 April.
Ferris missed Ireland's November internationals but, at one stage, appeared to be in with a chance of returning to Declan Kidney's squad for the closing rounds of the current Six Nations.
He suffered the injury in a Pro12 game against Edinburgh on 2 November when he twisted his right leg awkwardly after being tackled following one of his trademark surging charges.
However, Ulster stressed on Thursday that Ferris was expected to make a full and complete return to the game.
Ferris was selected for the 2009 British and Irish Lions squad but, after making a brilliant early impression in South Africa, suffered a knee injury which ended his tour.
He also missed the 2011 Six Nations campaign because of injury.