That game would have given him the chance to play against his 2009 Lions tour midfield partners Brian O'Driscoll and Gordon D'Arcy, but he will now have to sit out the near sell-out game at the Aviva Stadium.
He will also miss Wales' summer tour to Australia, where the 2012 RBS 6 Nations champions will play a three-Test series against the 2011 Tri-Nations winners, Australia. A year out from the Lions' 125th anniversary tour to Australia it would have been a great opportunity for Roberts to lay down a marker for inclusion.
But now he will have to watch from home as he fights to regain full fitness for both club and country at the start of the 2012/13 season.
"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've been looking forward to for a long time but unfortunately my body hasn't quite allowed me to be a part of such a huge occasion for us as a region," said Roberts.
"I originally injured my knee in Paris playing against Racing Metro after returning from the World Cup. With the fantastic help from the medical staff at the Blues and 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 (ACL) later this week. It will mean a minimum of roughly six months away from the playing field.
"I suppose it's a chance for me to get my body fully right for what is a huge season for both club and country, with a certain carrot at the end of it too. It will also allow me to continue my focus on the final year of my degree in medicine and the finals I'll be sitting next March."
It is another huge blow to the Blues, who earlier this week sacked Gavin Henson for inappropriate behaviour and will be without Wales' grand Slam skipper Sam Warburton because of a shoulder injury.
Dafydd Hewitt and Gavin Evans will now come into the reckoning to join All Black Casey Laulala in the centre for the Blues. Welsh cap Evans played most of the match in the win over Racing Metro in Paris and started in the team that won against the same opposition in Cardiff, while Hewitt started for the Blues in their win away to London Irish.