The game took a dramatic turn in a three-minute spell just before the interval when Sunderland snatched the lead and the Saddlers had Chris Baird sent off.
Marcus Stewart latched on to a headed pass from Jeff Whitley in the 42nd minute to surge through the middle and after switching the ball on to his favourite left foot, easily beat goalkeeper James Walker.
Then in the three minutes time added on at the end of the half, Baird brought down John Oster as the Wales international broke clear and referee Paul Robinson had no hesitation in showing the on-loan Southampton defender the red card.
Walsall had been strictly limited in their attacking ambitions and the dismissal of the Northern Ireland international further hindered their chances of at least salvaging a point.
The Black Cats, however, failed to press home their numerical advantage, wasting several clear-cut chances in a most one-side second half.
Walker made outstanding saves from Stewart and Oster to keep the Saddlers in the hunt and only a brilliant save by Mart Poom from Gary Birch denied the visitors a most unlikely 83rd minute equaliser.