Spurs were comfortable as they dominated Sunderland in the first half of a largely undistinguished encounter, but they failed to fully capitalise on their superiority.
Ben Davies' goal was a deserved reward, and it looked like Spurs would enjoy the luxury of a rare home victory to ease some of the ill-feeling towards Thomas Frank in the aftermath of the Brentford stalemate.
Instead, their slender lead became a burden as tension increased around the Tottenham Hotspur Stadium, Sunderland sensing the chance to exploit the nerves.
Spurs created opportunities after the break but were wasteful, leaving the door open for Sunderland to record another fine result in their excellent return to the Premier League.
Joao Palhinha's late header flew agonisingly wide for Spurs, leading to more loud jeers at the final whistle, the sound of frustration.