A second half red card for Bryan Oviedo allowed Peterborough to fightback and take a point at the Stadium of Light.
The Black Cats looked well set to take three points after an excellent opening 45 but the visitors fought back in the second and were aided significantly when Oviedo lashed out at Marcus Maddison.
They again showed their resilience and character to push for an unlikely winner but this draw means it is one win in six for Jack Ross' side.
Peterborough's outstanding away record may have set a few home nerves jangling in the build-up, particularly with Jack Ross missing a host of first team players through injury and
Early in the game at least, it seemed there had been little to worry about.
Though the visitors did serve notice of their counter-attacking threat early on, they were second best and Sunderland looked fluid, confident and threatening,
They had the lead early on when Chris Maguire escaped the attentions of two markers, wriggling free and teeing up Adam Matthews.
The full-back cut inside and found Josh Maja, who took the defender out of the game with his first touch before finishing emphatically.
After carving Peterborough open at will, Sunderland's only frustration at the break was that they hadn't added to their tally.
Aiden McGeady fired over as he ran into the box shortly after Maja's goal, before Jerome Sinclair missed a glorious chance.
It was a delightful move, started as Maguire played it out wide to McGeady. The Irishman drove towards goal and released Maja, whose first touch was a deft backheel. Sinclair looked
certain to score but could only turn the ball wide.
Unsurprisingly, Steve Evans rang the changes at the break.
He had moved away from his usual formation and it had flopped badly. Marcus Maddison and Joe Ward were introduced and immediately Sunderland were under the cosh.
Jon McLaughlin had to save well from both substitutes as the visitors applied immense pressure.
Sunderland began to reassert themselves but Oviedo's wild challenge gave Peterborough a major advantage.
Oviedo had chased the ball into the channel but after losing out, raised his boot at Maddison. The red was inevitable.
Posh were level within minutes, Ward racing onto a loose ball and leaving McLaughlin with no chance.
A pulsating conclusion followed.
Sunderland took a shock lead when Maguire again did superbly to get free down the right. He teed up Sinclair, who turned and fired into the roof of the net.
The lead last just minutes, however, as Ivan Toney beat the offside trap and turned a long ball past McLaughlin easily.
The Black Cats fought back again and looked like they could steal a late winner, but a Tom Flanagan header drifted agonisingly wide.
Sunderland XI: McLaughlin; Matthews, Flanagan, Baldwin, Oviedo; McGeouch, Power; McGeady, Maguire, Sinclair (Kimpioka, 90); Maja (James, 70)
Subs: Ruiter, Ozturk, Robson, Diamond, Mumba
Peterborough United XI: Chapman; Naismith, Tafazolli, Bennett, Daniel; Dembele (Maddison, 45), Woodyard, O’Hara, Cooke (Ward, 45); Cummings (Godden, 73), Toney
Subs: Tyler, Walker, Reed, Ward, Yorweth
Bookings: Power, 22 Toney, 86
Red Card: Oviedo, 68