London - Everton striker Jermaine Beckford's late equaliser piled on the misery for Chelsea as the champions dropped to third in the Premier League after a 1-1 draw at Stamford Bridge on Saturday.
Chelsea manager Carlo Ancelotti insisted this was a must-win game for his side and they appeared to be on course for a valuable victory when Didier Drogba put the home side ahead with a 42nd minute penalty.
But after dominating the first half, Chelsea were distinctly second best after the break and Everton were rewarded when Beckford finished after good work by Leighton Baines in the 86th minute.
Ancelotti's side had been toppled from the summit of the league table last weekend and with Arsenal beating Fulham, they now sit behind their London rivals and Manchester United following a dismal run of one win in six league games.
The return of skipper John Terry after a four-game injury lay-off together with Michael Essien's inclusion following a three-match ban ensured the home side carried a more determined look.
Everton pressed forward immediately with Louis Saha producing a good save from Petr Cech after just 20 seconds.
But Essien's presence helped Chelsea gradually assume control in midfield, while Nicolas Anelka's powerful running up front proved to be a constant threat for the home side.
Everton defended stoutly with central defenders Sylvain Distin and Phil Jagielka both in commanding form, although Chelsea made their first strong claim for a spot-kick in the 12th minute when Jose Bosingwa's low cross deflected against Distin's arm.
Chelsea's grip on the game may well have loosened had referee Lee Probert taken a dimmer view of Florent Malouda's petulant reaction to a tackle from behind from Phil Neville in the 24th minute.
The France midfielder turned and appeared to knee the Everton skipper in the face and it was to Neville's credit that he refused to make more of the incident and both players escaped with a ticking off.
Moments later Malouda was involved in his best effort on goal, delivering a left wing corner that led to Terry volleying against the visitors' crossbar.
Yet while Everton offered little going forward, it appeared they would succeed in fulfilling their first target of reaching half time on level terms until Neville misjudged a back pass five minutes before the break.
The full back didn't appear to see Anelka when he rolled the ball back to keeper Tim Howard.
The Chelsea striker reacted sharply, advanced into the area and pushed the ball past Howard before running into the keeper to win the penalty.
The referee decided the foul was worthy of only a yellow card despite Chelsea protests to the contrary and Drogba finished past Howard from the spot.
Everton clearly needed to adopt a more adventurous approach if they wanted to get back into the game and they finally worked up an impressive head of steam 15 minutes after the break when Jack Rodwell came close to levelling.
The Everton midfielder connected with Baines' cross and directed a header against the post.
Chelsea were left fuming when Tim Cahill slid in on Petr Cech and caught the keeper's face with his studs and the Australian was then involved in a spat with Terry.
That only confirmed the growing sense of anxiety among the home ranks.
And Ancelotti's side were eventually undone when Baines delivered another telling cross that was headed back across the goalmouth by Cahill where Beckford finished.