A late Jermain Defoe spot-kick gave Pompey the spoils in a game which the Wearsiders should have had wrapped up long before then.
It was a cruel blow for the Black Cats who had looked set to banish the blues from the previous week's 5-0 drubbing at the hands of Chelsea. In fact the hosts started like a house on fire and found themselves in front after just three minutes.
A Pompey attack broke down on the edge of the Sunderland 18-yard area and Dean Whitehead was quick to find Andy Reid.
The Republic of Ireland star hit a wonderfully weighted pass for Djibril Cisse and the Frenchman got goal-side of Sol Campbell before sliding the ball through the legs of goalkeeper David James and into the net.
It was exactly the start the home side wanted and they looked like the cats that had got the cream as they stepped up the tempo.
Roy Keane's men had threatened to run away with the clash in the first half as they bossed the early exchanges with some slick passing football.
They could easily have added to their tally in the opening 45 minutes had it not been for some good goalkeeping from James and the thickness of the goalposts.
Twice James did well to deny Cisse and Kieran Richardson was unlucky as his long-range effort struck the right-hand upright on 15 minutes.
The midfielder's 25-yard strike had James beaten all ends up, but Richardson and his team-mates could only look on as the ball ricocheted off the woodwork and out for a goal-kick.
These missed chances would prove costly as Pompey emerged with far more purpose after the break.
Much of the first half had passed Portsmouth by, but in the opening minutes of the second period the visitors stated their intention to make a game of it.
A wonder strike from Nadir Belhadj some 30 yards from goal levelled the scores on 50 minutes and for the first time in the match the away side began to push forward with purpose.
Sunderland though forced their way back into things and put plenty of pressure on their opponents. However, the breakthrough they all wanted eluded them.
Cisse did have the ball in the net on 63 minutes but the header was ruled out as the striker was correctly flagged offside.
The Black Cats continued to press while Pompey were restricted to infrequent breaks.
However, it was one such counter-attack from which they delivered the killer blow.
Glen Johnson was brought down just inside the area by El Hadji Diouf and referee Steve Bennett had no hesitation in pointing to the spot.
Up stepped Defoe to send Marton Fulop the wrong way and make his side's long trek back to the south a very happy one by securing all three points and the first win under Tony Adams.
Sunderland, on the other hand, were left to rue their missed opportunities and to wonder just where it had all gone wrong.