Having put nine goals past Wigan Athletic last week a tougher assignment was expected away to Southampton but, with scoring sensation Patrick Bamford again in top form, Forest crusied through by a 5-1 scoreline.
Bamford added to his five goal haul against the Latics with four to stun the Saints and again push his claims for a chance in a Forest first-team struggling for goals.
The Reds are now in the quarter-finals after another bright moment in a dismal season for the club provided by their young stars.