Chelsea's suicidal defending from set-pieces threatens to wreck their Barclays title ambitions as they drew 3-3 with Everton and failed to win for the fourth game in a row.
The Blues have now conceded 10 goals in their last four games and all three Everton strikes arrived courtesy of a Chelsea defence that looked clueless at free-kicks and throw-ins.
Everton became the first team this season to leave Stamford Bridge with any reward but Chelsea should have put this game beyond the Toffees long before half-time.
The Blues are now just three points clear of Manchester United who take on Aston Villa in the evening kick-off game.
Everton took a shock 12th minute lead when a Louis Saha header off a Leighton Baines free-kick hit the post and rebounded into the net off the back of Petr Cech.
But Chelsea hit back and goals from Didier Drogba and Nicolas Anelka put the Blues in front only for substitute Ayegbeni Yakubu to pounce from a throw-in to level the scores in first-half injury time.
Drogba restored Chelsea's lead but another blunder from a free-kick allowed Drogba's attempted clearance to bounce off the back of Saha to make it 3-3.
Chelsea almost took the lead in the fourth minute when Michael Ballack put Didier Drogba clear of the Everton defence but the Ivory Coast striker's effort was just wide of the far post.
But Everton hit back four minutes later when Jo unleashed 25-yard drive that Chelsea goalkeeper Petr Cech did well to turn away for a corner.
And the Toffees went in front in the 12th minute when the home side were again caught out from a set-piece.
Baines sent the free-kick into the penalty area and although Saha headed the ball on to the post, it rebounded off the back of Cech and into the net for an own goal.
It was only the second goal Chelsea had conceded in the Barclays Premier League this season.
Not since the opening day, when Hull's Stephen Hunt scored, had any opposing domestic side found the net.
It was the perfect tonic for an Everton side that has won just once in their last nine league games.
But Chelsea were level in the 17th minute with a simply worked goal.
Ricardo Carvalho broke forward and evaded a number of challenges before supplying a superb pass for Frank Lampard.
The England international tapped the ball into the path of Drogba who hit a first-time shot into the roof of the net for his 17th goal in all competitions this season.
Anelka then put Chelsea in front in the 23rd minute when Everton failed to clear Lampard's corner and Anelka collected Carvalho's neat pass and fired into the roof of the net from close range.
Everton striker Jo was forced to hobble off with an ankle injury in stoppage time and replacement, Yakubu, shocked Chelsea with an equaliser seconds later.
Terry failed to clear a throw-in and when the ball bounced off Carvalho, the Everton striker pounced.
After Wednesday's 2-2 draw with APOEL in midweek, coach Carlo Ancelotti called for his players to play with the same intensity for 90 minutes.
But Chelsea once again stopped playing when they had Everton on the ropes and the visitors had punished them again with Yakubu's equaliser some five minutes into first-half injury time.
Ancelotti resisted making any changes at half-time and began the second period in a positive fashion.
And in the 58th minute their pressure paid off when Branislav Ivanovic crossed for Drogba to score his 18th of the season.
The Ivory Coast striker fired home from six yards at the far post after Everton's defence failed to intercept the cross.
But astonishing Chelsea again committed defensive suicide in the 63rd minute with yet another set-piece blunder.
It was a comical affair as Heitinga sent over a free-kick into the Chelsea penalty area.
Drogba, helping out in a defensive role, headed the ball into the back of the leaping Saha and it bounced back over Cech and into the empty net to make it 3-3.
Ballack showed Chelsea could almost be as deadly from set-pieces when he forced Howard into a fine save with a 25-yard free-kick in the 74th minute.
But despite the home side's pressure, including another Ballack effort that flew just wide, they could not find a breakthrough and the doubts are growing over Chelsea's title credentials under Ancelotti.
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