The Blues defender was forced off in the second-half of Saturday's home fixture against Barnsley and the extent of the Spaniard's injury has now been revealed.
Meanwhile left-back David Murphy is awaiting the results of a scan on the hamstring injury that resulted in him being substituted in the 25th minute of the match against the Tykes.
To make matters worse for Blues, striker Marlon King is suffering with a virus and will continue to be assessed ahead of this weekend's trip to Brighton & Hove Albion.