Ireland wing Tommy Bowe has been ruled out for around four months after undergoing surgery on his injured knee.
Bowe was carried off during Ulster's Heineken Cup home defeat against Northampton last weekend and will miss the Six Nations as a result of the injury.
But he should however have time to recover full fitness in time for next summer's Lions tour of Australia.
Ulster said in a statement: "Tommy Bowe has undergone successful surgery on his knee and is now expected to be out for approximately four months.
"The winger sustained significant lateral ligament damage to his right knee in the closing stages of Ulster's 10-9 Heineken Cup loss to Northampton."
The news is a big blow to Ulster, who Bowe re-joined in the summer, and Ireland boss Declan Kidney.
Brian O'Driscoll, Paul O'Connell, Sean O'Brien and Stephen Ferris all missed he recent autumn Test schedule, which Ireland ended with an impressive victory over Argentina.
But fears that he would miss the Lions tour have proved unfounded, a major boost to head coach Warren Gatland.
Provided he does recover in time, Bowe will be one of the favourites for a starting place in the Lions back line.