Sunderland keeper Craig Gordon has been ruled out of action for the next six months after undergoing knee surgery in Sweden.

Gordon, signed by Sunderland from Heart of Midlothian in 2007, had the surgery done by Professor Hakan Alfredson and is likely to miss the start of next season as he begins his recovery.

Gordon is therefore almost certain to miss Scotland’s upcoming Nations Cup games as well as further key European fixtures against Czech Republic and Liechtenstein.

In addition, he is also likely to miss Scotland’s international friendly against Denmark.