Middlesbrough midfielder Kevin Thomson will have an ankle operation on Monday that is likely to rule him out for up to 12 weeks.
The 26-year-old picked up the injury while running on a treadmill and has also aggravated tissue around a previous fibula injury.
"It's half an ankle problem and half a return to the fracture site," boss Tony Mowbray told the club website.
"Hopefully, he'll be back strong and fit and we'll put an end to the problem."
But it means Thomson will almost certainly miss Scotland's friendly against Denmark on 12 August and will be doubtful for the Euro 2012 double-header the following month.
The Scots host Czech Republic on 3 September and Lithuania three days later in games that could decide the runner-up spot behind Spain in Group I.
Thomson, who joined Middlesbrough from Rangers in July 2010, was restricted to just 19 appearances in his debut campaign on Teesside by a string of niggly injuries.
After breaking his leg against Leicester in only his second appearance, the Scotland international endured several set-backs over the course of the season.
However Edinburgh-born Thomson returned from a four-month lay-off to feature in the final seven games of the campaign.
"We won the last four games on the bounce and lost only once in the last 12," Mowbray added.
"Kevin was instrumental in that and he was looking forward to getting started this year and showing everyone what he's capable of.
"He took it pretty badly but injury is part and parcel of football and you have to deal with it.
"Having worked with him before I know what a talent he is, but hopefully we'll have a 100% fit Kevin Thomson in a few weeks."