"I had a scan on Saturday morning and I was told then that it was the cruciate. I'll have an operation in the next three or four weeks and it will mean I'll miss the first three or four months of next season," he told the club's official website.
"Christmas is the target for me now. If I'm back before then, it'll be a bonus. I'm really disappointed, but when I'm fit and back in contention, I'll look to build on what I've done this season."