Middlesbrough midfielder Kevin Thomson is facing up to 12 weeks on the sidelines as he prepares to undergo ankle surgery on Monday.
The 26-year-old Scotland international, who missed much of last season with a fractured fibula, aggravated that injury and damaged his ankle when he stumbled off a treadmill.
Manager Tony Mowbray said: "Kevin had a lot of problems last year and he was getting himself ready and stumbled off a running machine and twisted his ankle."
He added: "It's half an ankle problem and half a return to the fracture site. We are looking at maybe 10-12 weeks and hopefully he will be back strong and fit and we will put an end to the problem.
"He's been in London having proper research on it. Hopefully we are at the root of it now and we can sort it out in the next couple of months.
"He took it pretty badly, but injury is part and parcel of football and you have to deal with it."
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