The Wales star suffered a hyperextension of his elbow in last weekend’s agonising 14-12 defeat to Australia.
He saw a specialist yesterday and is expected to be out of action for up to six weeks.
The powerful centre heads an alarming injury list for the Blues, who are also without Leigh Halfpenny and Bradley Davies.
Halfpenny is recovering from a severe stinger and continues to be assesses and Davies is expected to return to training next week following severe concussion.
Michael Patterson, Dan Fish, Andi Kyriacou and Tom James are also recent additions to the treatment room and are likely to miss the back-to-back clashes with Montpellier.
Blues director of rugby Phil Davies admits the injuries are frustrating but he has urged his fringe players to step up and prove a point.
“Only a fortnight ago things were looking very positive for us, when we were welcoming back some key players,” said Davies.
‘However, we have been extremely unfortunate to pick up a raft of injuries in the last few weeks.
“It is frustrating that we cannot select from a full strength squad for these crucial matches, but on a positive note, it gives a chance for some of our other players to step up and show what they can do.
“Montpellier has a formidable reputation in the French league as a very physical team with an extremely strong set-piece.
“Their scrum is particularly strong this season, having won all 17 of their put-ins so far in both Heineken Cup games and their six lineout steals is a joint high this season.
“These are areas in which we will have to be at our best if we are to compete this Sunday.”
