However, the hosts couldn't hold on and Spurs equalized when Kyle Walker's left-wing corner was headed into his own net by Cuellar in the 48th as he leapt for the ball with one of his teammates.
And four minutes later, Tottenham was celebrating again following a superb piece of individual skill by Lennon.
His attempted one-two with Sandro failed to come off but he pounced on a loose ball, rounded O'Shea and curled his shot in at the near post.
Sunderland goalkeeper Simon Mignolet made a fine save from Defoe, who should have scored from inside the six-yard box, and then from Adebayor when the Togolese striker went through one-on-one.
The only negative for Spurs came when Bale was booked for diving in the area with 10 minutes left — it was his fifth booking of the season and he will miss Tuesday's home match against Reading.