The double strike killed off the match as a competitive spectacle, although Jermaine Pennant flashed in a couple of long-range free-kicks to give Birmingham some hope.
Asamoah Gyan regained the lead for Sunderland after the break, but the visitors sat back and finally buckled under a barrage of long throws and set-pieces, as two Jermaine Pennant free-kicks set up Huth to score twice in the last seven minutes and seal a remarkable recovery.