Arsenal have missed out on the chance to top the Premier League table after letting a one-goal lead slip away to lose 2-1 against Everton at Goodison Park.
The Gunners took the lead through a deflected Alexis Sanchez free kick, before goals from Seamus Coleman and Ashley Williams turned the game on its head.
Defeat for the visitors ends their 14-match unbeaten run in the top flight stretching back to the opening weekend, meaning that Chelsea remain three points clear at the summit with a game in hand to come against Sunderland tomorrow night.
Both sides found themselves in promising positions in the early stages of the match, with Mesut Ozil sending a shot over the bar from 10 yards out and Romelu Lukaku failing to find a teammate when played in behind down the right.
Home supporters were on edge for the opening quarter of the game, which is perhaps explained by the fact that their side have gone into half time a goal down in five of their last six games here.
It looked like being the same old story for the Toffees 20 minutes in when, after Phil Jagielka wiped out Francis Coquelin on the edge of the box, Sanchez sent a free kick past Maarten Stekelenburg via a big deflection off eventual match-winner Williams.
Everton battled back well, however, and were soon the side on top as Arsenal started to sit back a little more to hold off the direct running from wide positions.
Aaron Lennon, one of four players brought back into the starting lineup tonight, perhaps should have done better five minutes before the interval when skewing a shot wide of goal from inside the box.
The breakthrough goal for Everton did arrive before the break courtesy of Coleman, who simply drifted into the box and got on the end of fellow full-back Leighton Baines's left-sided cross, delicately heading the ball into the bottom corner of the net to level things up on Merseyside.
Things boiled over as the players made their way down the tiny tunnel area at the end of the first half, but it was Arsenal who were the more fired up early on in the second period.
Another glorious chance passed Ozil by, again coming from a Sanchez pull-back from out wide which he this time curled over the target from 15 yards out.
Everton again found their feet following a fairly tepid start, with Ross Barkley dragging a shot wide of the far post when getting on the end of a Lukaku knockdown to send out a little warning to Arsenal on the hour mark.
It took until the 64th minute before either keeper had anything to do in a tight second half, as Enner Valencia's cross on his first Premier League start of the season deflected off Gabriel Paulista into the hands of Cech.
Arsenal, with just two defeats in 24 this season in all competitions prior to this loss, were struggling to really get their advanced players on the ball, and Arsene Wenger turned to his reinforcements for the final quarter of the game.
Alex Iwobi and Olivier Giroud, who had scored five goals in his last six against Everton, were introduced, but it was the Toffees who looked the more likely to find a second over the next 10 minutes.
Iwobi did send a shot into the side-netting soon after, but it was still Everton who looked the more confident of the two sides and they were rewarded for their positive attitude late on.
Jagielka was denied by Cech from close range when a corner kick fell nicely into his path, yet Arsenal did not heed the warning and from the next delivery Williams headed in unmarked to win the contest for his side - the second time he has done so against the Gunners this year, having also dented their title hopes while with Swansea City last season.
More late drama was to follow, as Jagielka was shown a second yellow late on before Arsenal had two shots blocked on the line in quick succession right at the death, Everton doing enough to pick up just a second win in 11 and maintaining their impressive form on home soil.
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