Rangers goalkeeper McGregor and Derby midfielder Stephen Pearson have become the latest players to pull out.

Gavin Rae has been called up after the duo joined Gers trio Ferguson, McCulloch and Dailly on the sidelines, although the cause of their withdrawal is as yet unclear.

Ferguson saw a specialist in England last week with an ankle problem which has been troubling him for several weeks.

An injection saw him through the SPL win over Hibernian on Saturday but he will play no part in the game at Hampden.

McCulloch also misses out after a thigh injury flared up following the weekend action, while an X-ray has revealed Dailly is suffering from a broken toe.

All three will now receive treatment at Murray Park and are expected to be fit in time for this weekend's Old Firm derby, according to the club's official website.

Striker Kris Boyd remains in the national team squad as George Burley prepares to make his debut as Scotland manager.

Celtic midfielder Barry Robson has also announced his withdrawal from the squad, although no reason has as yet been given.

Scotland, meanwhile, have announced they will play Northern Ireland at Hampden Park on August 20.

Burley's men will also take on the Czech Republic in Prague on May 30, and have a reciprocal agreement to play the Czechs at Hampden on March 3 2010.