Celtic captain Scott Brown has admitted that he was "devastated" to learn of his latest injury which is likely to keep him out for three months.
The 30-year-old midfielder damaged knee ligaments against Kilmarnock last weekend as he made his return from a different knee complaint which had kept him out for four matches.
Although Brown is likely to miss three months of action, he is hopeful that surgery will not be needed.
"I was a bit devastated," Brown told the club website. "When I woke up in the morning, I had a wee feeling it was my ligament.
"I had hoped it was a wee strain but it was a bit more serious than that. I will be on crutches and my leg will be in a brace for four weeks and then after that I will see how it's healing.
"If it's healing well it will be good news and I won't need an operation, but if it's not going so well I might have to go down the operation route."
Brown's injury means that he is unable to feature for Celtic in their crucial Europa League tie against Ajax this evening.