Arsenal maintained their challenge for a first trophy in nine seasons when they beat Liverpool 2-0 at the Emirates Stadium to open up a five-point lead at the top of the Premier League on Saturday.
A brilliantly taken opener from Santi Cazorla, who smacked in a rebound after 19 minutes, and an even better goal from Aaron Ramsey, who struck a swerving shot with the outside of his right boot after 59 minutes, took Arsenal to 25 points from their 10 matches.
Chelsea, who lost 2-0 at Newcastle United after winning their previous six games in all competitions, are second, level on 20 points with third-placed Liverpool.
They were full of confidence, they have been in fine form and they showed that early on, but we managed to weather the storm and got the goals
But Chelsea's performance did not please their boss, Jose Mourinho, who said: "I did not like my team today, I am disappointed."
Manchester City, who beat Norwich City 7-0 at the Etihad Stadium; Southampton, who drew 1-1 at Stoke; and Tottenham Hotspur, who play at Everton on Sunday, all have 19 points, but Spurs can move into second place on 22 if they win at Everton on Sunday.
Champions Manchester United continued their improvement after their sluggish start to the season with a 3-1 win at Fulham, and although they stayed eighth, they gained points on some of the teams above them.
Liverpool, who had won three of their last four league games and drawn the other, started brightly at Arsenal but the home side took a grip on the game after breaking the deadlock.
Ramsey, who has now scored 10 goals this season, told BT Sport: "We got stuck into them and managed to get a goal early, which put us in good shape for the second half, and we managed to finish the job.
"They were full of confidence, they have been in fine form and they showed that early on, but we managed to weather the storm and got the goals."