The 33-year-old was forced off in the first half of the club's FA Cup third-round tie at Premier League rivals QPR and will be forced to undergo knee surgery to heal the problem.

The club revealed the Hungary international ruptured his anterior cruciate ligament in his left knee - with a rehab time of around six to nine months.

Manager Steve Clarke has wished him a speedy recovery.

"I'm devastated for Zoltan," Clarke told the club's official website. "He's a terrific guy and professional and I want to thank him for his contribution this season. It has been invaluable.

"He'll now get our full support during the rehab process. Zoltan has already proven he can come back from this injury once and produce at the highest level and I have no doubts he will do so again."

Gera has netted four times in 18 appearances for the club this season - with all his goals coming in four separate league wins.