Chelsea 2-2 Tottenham
Gylfi Sigurdsson's late equaliser earned Tottenham a point at Chelsea, but Spurs missed the chance to climb into the Premier League's top four.
Goals from Oscar and Ramires, either side of Emmanuel Adebayor's finish, looked like they would seal a Champions League spot for Rafael Benitez's side.
But Sigurdsson's strike 10 minutes from the end lifted fifth-placed Spurs to within a point of Arsenal in fourth.
Chelsea remain third and are two points clear of the Gunners.
This was the game in hand that Chelsea and Tottenham had over rivals Arsenal, yet it was a good result for Arsene Wenger's team and it means Spurs' chances are now out of their own hands.
All three contenders now have two games left in their fight for the two remaining Champions League places.
For long periods of a free-flowing game, Chelsea were the superior team and looked capable of picking up the three points that would have all but guaranteed a top-four berth.
Not only did they conjure up two clever goals before the break, but they had several opportunities to put the game out of sight after the interval.
As the game wore on, though, Chelsea tired, perhaps understandably so when playing their 66th game of the season.
And in scoring one superb goal and creating another, Adebayor had an inspired game, during an evening when PFA and Football Writers' Player of the Year Gareth Bale was subdued.
Chelsea, who maintained an unbeaten run against Tottenham at Stamford Bridge that stretches back to 1990, began the match at a frantic pace with Juan Mata shooting over twice either side of Chelsea's opener.
When it came after 10 minutes, it was the Spaniard who supplied the corner, with Gary Cahill flicking on for Oscar to head in at the back post.
Spurs probed in the first half too, with Lewis Holtby and Kyle Walker just off target.
With 11 league goals in his last 11 appearances, Bale has been the chief contributor to Tottenham's Champions League ambitions, but he was well marshalled by the Chelsea defence early on.
And Adebayor stepped out the Welshman's shadow after 26 minutes to score a goal which matched some of Bale's superb strikes this season.
The Chelsea defence backed off, in part down to a clever run by Aaron Lennon, but the Togolese player took full advantage by curling his strike deftly into the top corner from 25 yards.
The hosts' lead was restored seven minutes before the break with another good goal, this time from Ramires, who beat Hugo Lloris with a toe-poke after being played through by Fernando Torres.
Although Torres could not end his Premier League goal drought, the Spanish forward was proving a menace as Chelsea threatened the Spurs goal several times after the break.
The 'Three Amigos' of Mata, Oscar and Eden Hazard were sweeping through the Tottenham midfield but a Ramires slip denied Chelsea a further goal, the Brazilian losing his footing when he was set to shoot.
Given that Chelsea played nine games in April, their energy was admirable and their lead looked comfortable.
But their concentration appeared to dip towards the end and Tottenham stole a hugely valuable point when Benoit Assou-Ekotto fed Adebayor and a smart backheel set up substitute Sigurdsson for a smartly-taken goal.
Bale fired over as Spurs searched for a winner but a draw was still a decent return after Chelsea wasted so many chances.