London Irish's former Ireland scrum-half Tomas O'Leary is unlikely to play again this season because of a serious back problem.
The 29-year-old has not played since October 28, and has undergone surgery on his lower back for what they describe as a "degenerative pre-existing injury" that has deteriorated this term. He faces "a four to six-month lay-off".
He was selected to tour South Africa with the 2009 Lions but he suffered a broken ankle just a month before the three-Test trip, and was ruled out of the tour. He recovered, but then lost his place with Ireland and Munster, and was a shock omission from the squad for last year's World Cup.
London Irish said in a statement: "Tomas originally suffered an injury to his lower back in the Aviva Premiership match with Northampton Saints on October 6 and aggravated it during the first half of the match with Harlequins on October 28.
"Following further medical examination the decision was taken that surgery was necessary to solve this problem.
"He is not expected to be available for selection until April 2013 at the earliest."
Meanwhile, Ireland have learnt who will referee their Six Nations games.