Blues blow away frail Arsenal
Two goals from Didier Drogba and a Thomas Vermaelen own goal made the difference as Arsenal were left 11 points off the pace.
Arsenal had won their previous 11 home games in all competitions but, after losing at Sunderland last week, they again struggled to make an impression on a Chelsea defence that has conceded just eight goals in 14 league games.
The match encapsulated the key differences between the two London sides as Chelsea's powerful lineup outmuscled Arsenal's lightweights and, when in sight of goal, went for the jugular.
In contrast, Arsenal were content to play endless passes around the box in attacks that all too often petered out thanks to over-elaboration.
Chelsea, who have also beaten Manchester United and Liverpool this season, top the standings on 36 points, five clear of United.
Tottenham Hotspur are third on 26 with Arsenal fourth on 25 and Liverpool, who won 2-0 at Everton on Sunday, fifth on 23.
There was barely an effort on goal in the opening 40 minutes at the Emirates but the game exploded into life with two near-identical goals in the last four minutes of the half.
The first came when Ashley Cole whipped in a low cross and Drogba steered a side-footed volley into the roof of the net.
Former Arsenal man Cole, relentlessly booed by the home fans, repeated the delivery three minutes later and in an attempt to prevent the ball reaching Drogba, Vermaelen deflected in an own goal in the same spot as the opener.
Arsenal did have the ball in the net four minutes after the restart but Andrei Arshavin's goal was ruled out for a high-footed challenge on Petr Cech by Eduardo.
After Arsenal eventually passed themselves into exhaustion, Drogba completed the impressive victory by planting a free kick beyond the diving keeper four minutes from time.
Arsenal manager Arsene Wenger described the scoreline as a "very unfair reflection of the game" and was particularly aggrieved by the disallowed goal.
"It was a Chelsea player stopping the ball, the referee made a massive mistake when you start the second half at 2-1 instead of 2-0 it's psychologically important," he told reporters.
Wenger rejected the idea that his players had been bullied out of the match, saying: "Chelsea are physically strong but it's too easy to have that impression. If you look at the analysis you will be surprised, that is not what won them the game."
Even two-goal Drogba did not escape his ire. "He doesn't do a lot, he didn't touch the ball a lot today," he said, adding that he thought his first goal was a mis-hit.
Chelsea boss Carlo Ancelotti was also reluctant to dwell on the physical aspect of his team's display.
"We have a physical quality but we have other qualities too. Our midfield won the game and we defended with intelligence," he said.
"It's true that Arsenal kept the ball for the first half but when we got possession we were very good on the counter-attack."
In the day's other big derby Liverpool ended a bleak