Simon Cox struck a superb late equaliser as West Brom dealt a major blow to Tottenham's hopes of Champions League qualification.
Jermain Defoe's fine individual goal looked to have secured all three points for the hosts, but substitute Cox curled a shot past Heurelho Gomes from the edge of the area in the 82nd minute.
The result leaves Spurs one point behind fourth-placed Manchester City, who will play their game in hand at Blackburn on Monday.
And with Harry Redknapp's men still facing trips to Chelsea, City and Liverpool, their chances of reaching the Champions League for the second season in a row appear to be fading fast.
For West Brom, a point at White Hart Lane was further evidence of the turnaround engineered by Roy Hodgson since his arrival in February.
The former Liverpool boss has only tasted defeat once in nine games and has steered his side to the safety of mid-table, where they now sit 12th with 40 points.
The Baggies made a stunning start to the game in blazing sunshine in north London.
They had already threatened through Jerome Thomas before Peter Odemwingie gave them the lead after five minutes.
The goal owed much to the vision of Arsenal loanee Carlos Vela, who picked out Odemwingie with a pin-point cross-field pass before the Nigerian shrugged off the challenge of Benoit Assou-Ekotto and curled a shot inside Heurelho Gomes' far post.
Assou-Ekotto was injured in the collision with Odemwingie and had to be replaced by Sandro, meaning Gareth Bale - a surprise starter in the Tottenham line-up after sustaining a knee injury against Arsenal in midweek - was forced to revert to left-back.
But the newly-crowned PFA Player of the Year did not seem to lose any of his attacking instincts as he galloped down the flank before crossing for Roman Pavlyuchenko, whose glancing header fizzed across the face of goal.
The Russian did not have to wait long for his goal as Spurs gained their reward for a dominant spell of attacking football.
Tom Huddlestone's pass was deflected into the path of Pavlyuchenko, who cleverly engineered some space for himself on the edge of the penalty area before lashing a low drive in off the post.
Pavlyuchenko should have put his side ahead shortly afterwards. Scott Carson pushed Rafael van der Vaart's fierce strike into his path but he side-footed the ball over the bar with the goal at his mercy.
With Bale rampant down the left and Luka Modric influential in midfield, the Baggies were relieved to see the game through to half-time, although they suffered a blow when midfielder Steven Reid was forced off injured and replaced by Gonzalo Jara.
Spurs were grateful to the athleticism of Gomes after the break as he flew to his right to palm away a powerful header from Odemwingie after Nicky Shorey's cross from the left.
With their supporters just starting to express their displeasure at his players, Spurs boss Redknapp introduced Aaron Lennon for Huddlestone and the England winger soon won a free-kick on the edge of the area, which Van der Vaart curled harmlessly over the bar.
Any disappointment was short-lived, however, as Defoe put the hosts ahead with a superb strike.
Collecting the ball some 40 yards from goal, the England striker shimmied his way to the edge of the box and rifled a left-footed drive past Carson's outstretched hand.
Hodgson responded by withdrawing midfielder Paul Scharner and bringing on striker Cox, who repaid his manager's faith with a sublime equaliser.
Picking up the ball on the left flank, he cut inside and curled it over Gomes and into the far top corner.
The goal seemed to take the stuffing out of Spurs, who failed to engineer another chance of note - in fact it was Odemwingie who came closest to grabbing a winner as his low drive fizzed narrowly wide.
With just one win in seven games, Redknapp has his work cut out to rouse Spurs for one last push towards the top four. After this damaging draw, City are firmly in the driving seat.
Tottenham boss Harry Redknapp:
"We're obviously disappointed because we thought we were in good shape 2-1 up, but Simon Cox has scored a world-class goal to equalise.
"It's difficult winning games in this league and West Brom are a good side.
"We moved the ball about well but we've got no divine right to win games. We'll try and make the top four and if we don't we'll try again next year."