Steven Fletcher's participation in Scotland's friendly with Poland in Warsaw next month is in doubt due to an Achilles problem.

The striker missed Sunderland's Barclays Premier League victory over Newcastle United last weekend and Gus Poyet, his manager, has admitted the injury, which has been troubling the 26-year-old for weeks, is worse than first thought and could require surgery. Poyet said: "It's affecting him more than I thought. I'm a bit worried. We're analysing it with the medical staff but we're going to have to make a decision one way or the other.

"We'll have to look at the games ahead and the chance of rest in between but we'll need to make a decision."