Cardiff Blues and Wales centre Jamie Roberts will miss the rest of the season and his country's summer tour to Australia after it was decided that he needs to undergo knee surgery.
Roberts originally picked up a knee problem in the Heineken Cup win over Racing Metro in November and suffered another injury to the same knee in Friday's 31-3 defeat against Glasgow, and needs surgery on his anterior cruciate ligament.
He will miss this weekend's daunting Heineken Cup quarter-final against Leinster, with Dafydd Hewitt or Gavin Evans set to deputise.
Gavin Henson would have been a potential replacement but he was sacked by the Blues on Monday for his alcohol-fuelled behaviour on the flight back from Glasgow
A Blues statement read: "Cardiff Blues can confirm that Blues and Wales centre Jamie Roberts will require surgery on his knee and will miss the rest of the season."
Roberts added: "First and foremost, I'm pretty devastated to be missing this weekend's Heineken Cup quarter-final match against Leinster, in what is our biggest match of the season.
"It's a match I have been looking forward to for a long time but unfortunately my body hasn't quite allowed me to be part of such a huge occasion for us as a region.
"I originally injured my knee in Paris against Racing Metro after returning from the World Cup. With the fantastic help from the medical staff at the Blues and the Welsh Rugby Union, I was able to rehab my knee well enough to get me through a handful of games for the Blues and the successful Grand Slam Six Nations campaign with Wales.
"However, following my injury in the match against Glasgow on Friday night I've been advised by the knee surgeon that my knee is now not stable enough to continue playing and potentially risk further injury to the knee.
"The decision has been made for me to have an operation on the anterior cruciate ligament later this week. It will mean a minimum of roughly six months away from the playing field."