With both clubs on a five-match losing streak something had to give and it was Blues who emerged victors at a chilly Stadium Of Light.
Blues boss Steve Bruce dropped goalkeeper Maik Taylor after a run of poor form, recalling Nico Vaesen, and was able to bring back Mario Melchiot, David Dunn and Damien Johnson after injury.
However, it was Bruce's three second-half substitutes that played a part in the all-important goal in the 67th minute, Jemaine Pennant crossing from the right for Walter Pandiani to power in a header that was beaten out by Black Cats goalkeeper Ben Alnwick, only for Julian Gray to sweep the loose ball into the empty net.
In a dull first half Jonathan Stead produced a fine save from Vaesen but the Blues missed the best chance to break the deadlock as early as the 15th minute when Neil Kilkenny was sent clear from Matthew Upson's long punt forward.
The young Blues midfielder dwelt on the ball when well positioned and allowed Gary Breen to get in an all-important challenge.
Alnwick then collided with Breen and the teenage keeper flapped nervously at a cross-cum-shot from Dunn.
Stead cut in dangerously from the left but Muzzy Izzet forced the ball behind for a corner and Christian Bassila fired wide as Sunderland huffed and puffed without any conviction.
McCarthy brought on Liam Lawrence at the start of the second half for Andy Welsh and Chris Brown for thAnthony Le Tallec, but the changes introduced by Bruce proved more decisive.
Pandiani's pace and power was matched by the fleet-footed Pennant, yet it was Gray who emerged the hero with his first goal of the season.
Blues really should have added to their one goal lead with Emile Heskey and Pandiani both going close to doubling the advantage.
Brown almost salvaged a point for the Black Cats late-on, the impressive Vaesen diving to his left to turn a crisp drive behind for a corner.