The Serbian defender missed half of the previous campaign after injuring his cruciate ligament against Basel in the Champions League in December.

The centre-back made his return at the start of the campaign and featured five times before undergoing further surgery, which will keep him out for another two months, something that has not surprised his manager.

"I don't think he was ever 100 percent," Ferguson told reporters. "I noticed a couple of times in training that he was limping a little bit - then he started feeling tightness in his knee.

"He wanted to carry on and in that situation that is what tough guys can do.

"Obviously the main operation was to correct the cruciate but when you do cruciates there is always the danger that the cartilage or meniscus is damaged also and that was the case."