CHELSEA missed a golden opportunity to shut the door on lingering doubts about their qualification for next year's Champions League – twice allowing Spurs to level in a breathless encounter.
For most of the match, the Blues appeared on course for the win that would effectively guarantee their participation in Europe's premier competition next season.
Oscar (pictured) and Ramires both scored during an impressive first half.
But they were undone 10 minutes from time and now may no longer go to Amsterdam next week with domestic matters all done and dusted.
They should really have put Spurs out of sight, given their overall panache, although they did visibly tire in the latter stages of the second half, which was hardly surprising given their punishing schedule.
Chelsea were irresistible in the opening 25 minutes, with Spurs barely able to get out of their own half – let alone engineer Gareth Bale into dangerous areas.
And yet, the visitors were somehow on level terms after 26 minutes as Emmanuel Abebayor ended a counter-attack from deep in his own half by curling a perfect shot over Petr Cech from 25 yards.
The goal came when Scott Parker broke up a Chelsea attack to set the move in motion and from nowhere, Tottenham were back in business.
A very different script looked ready to unfold when the Blues, roared on by a particularly raucous Matthew Harding end, grabbed the lead after only 10 minutes - Oscar stooping to head in from three yards after Gary Cahill had outjumped Michael Dawson to reach Juan Mata's inswinging corner.
Eden Hazard and Oscar momentarily lost the bite that had been a feature of the opening salvoes, during which Mata had fired just over a couple of times.
But normal service was resumed after 39 minutes when Ramires showed superb technique to poke a shot across Hugo Lloris and into the far corner after racing onto a finely weighted pass from Fernando Torres. Ramires had started the move himself by spreading the ball to Oscar on the right flank.
The goal had the Chelsea engine purring again and more great play ended with Oscar curling a shot at the keeper.
It was no longer one-way traffic though and Abebayor skied over before setting up Kyle Walker for a low left footer that went narrowly wide.
Chelsea were soon being the aggressor again at the start of the second half, with a curling cross from Cesar Azpilicueta almost catching the inside of the far post - Lloris beaten by the flight.
Then Hazard fired over from the edge of the six yard box, with the unmarked Torres waiting in vain for a cross.
Another raid set up by a sumptuous flick from Hazard ended with Ramires losing his footing when poised to pull the trigger – Mata having rolled the ball to the Brazilian with an invitation to put the game out of Spurs' reach.
It was to prove costly. With 10 minutes to go, Benoit Assou-Ekotto played a ball towards a marginally offside Adebayor, whose clever backheel found sub Gylfi Sigurdsson in space, and the Icelander drilled inside the far post to make it 2-2.
The evening was full to brimming with sub-plots and intrigue, with Andre Villas-Boas returning to a club he this week accused of playing 'invisible' football.
Would Spurs get a first win at the Bridge since 1990? Who would snatch the vital points needed to aid Champions League qualification? And could the game come out of the inevitable shadow cast by the seismic news of Alex Ferguson's retirement?
The answer was an emphatic yes. The game was as frantic and riveting as all derbies with Spurs tend to be, but also full of great quality. In the end, though, it was not quite the result the Blues wanted.
Line up: Cech; Azpilicueta, Cahill, Ivanovic, Cole; Ramires, David Luiz; Oscar (Benayoun 84), Mata, Hazard (Moses 73); Torres. Subs not used: Turnbull, Lampard, Terry, Ba, Ake.