Hatem Ben Arfa was brought down by a combination of Rafa van der Vaart and Aaron Lennon in the 80th minute and picked himself up to slot home the winner from the spot.
It was a hammer blow just minutes after we'd scored the equaliser our play deserved as Jermain Defoe struck from close range.
The result didn't do justice to our performance at the Sports Direct Arena.
Jermain Defoe and Gareth Bale hit the woodwork in the first half and Tim Krul was the busier goalkeeper throughout as we registered 12 efforts to Newcastle's six.
But we were undone by a moment of magic from Demba Ba in the 55th minute and then the penalty.
Andre Villas-Boas opted for William Gallas and Younes Kaboul in central defence, Sandro, back in the fold for the first time this summer, joined Jake Livermore in midfield and Gylfi Sigurdsson played in behind lone striker Jermain Defoe.
We were quickly into our stride in a cauldron of an atmosphere with Kyle Walker's willingness to get down the right flank apparent from the off.
Newcastle's best chance of the half was the first serious effort of note as Demba Ba's somewhat tame effort struck Papiss Cisse and the 22 players joined 50,000 fans in watching the ball roll agonisingly just wide.
Sigurdsson's free-kick had Tim Krul scrambling to his right to tip wide after 26 minutes and the goalkeeper was helpless in our next attack as Sandro won possession, Sigurdsson rolled into the path of Defoe and the striker hit a low shot that cannoned back off the upright.
Five minutes later and we were thinking was might have been again as Benoit Assou-Ekotto switched play wide to Aaron Lennon, he skipped past Davide Santon and chipped to the far post where Bale planted his header back over Krul, only for it to strike the crossbar.
We looked dangerous on the break and sprung Newcastle again after 40 minutes as Lennon picked up Brad Friedel's punch, Sigurdsson again found Defoe who turned sharply before firing a yard over from the edge of the box.
The second half followed a similar pattern before Ba broke the deadlock. Walker headed Danny Simpson's cross into the air, Ba pulled the ball down and cushioned a volley over Friedel and into the far corner.
Undetered, we continued to press. Sigurdsson curled wide before being replaced by van der Vaart, who immediately picked out Lennon's run but Perch was back to clear again.
Walker steamed through two 50-50 challenges before rolling into Defoe but Krul got down well low to his left to touch the ball wide.
Defoe saw another 20-yarder deflected wide but was soon on target. Lennon picked up the ball on the left and teased in a cross to the far post, Santon misplaced his header towards his own goal, Krul did well to keep it out via the post but Defoe was there to bury the rebound.
That might have proved the spark to go on and win maximum points but the game turned against us just three minutes later.
Ben Arfa looked to get between Lennon and van der Vaart on the left edge of the box, went down and referee Mr Atkinson pointed to the spot. Ben Arfa sent Friedel the wrong way from 12 yards.
Friedel did well to tip over Jonas Gutierrez's 30-yarder and but for a couple of flourishes, that was that.
Newcastle (4-4-2): Krul; Simpson, S Taylor, Perch, Santon; Ben Arfa, Cabaye (Anita, 71), Tiote, Gutierrez; Ba (Obertan, 85), Cisse. Unused subs: Harper, Williamson, Gosling, R Taylor, Amilfitano.
Spurs (4-2-3-1): Friedel; Walker, Gallas, Kaboul, Assou-Ekotto; Livermore, Sandro (Kane, 85); Lennon, Sigurdsson (van der Vaart, 69), Bale; Defoe. Unused subs: Cudicini, Naughton, Vertonghen, Jenas, Townsend.
Goals: Newcastle - Ba (55); Ben Arfa (penalty, 80); Spurs - Defoe (76).
Yellow cards: Newcastle - Simpson (14), Cabaye (45+2), Spurs - Livermore (17), Sandro (19).
Referee: Mr M Atkinson.