A Didier Drogba brace and an own goal from Thomas Vermaelen secured a seventh successive win for the Blues and dealt a severe blow to Arsenal's title hopes.

Chelsea's next league match comes against big-spending Manchester City at Eastlands and Ancelotti is adamant his players must maintain their focus if they are to stay on top.

"It is important for me that Chelsea continue to play as we did (against Arsenal) with determination and concentration," the 50-year-old said.

"We know very well our possibilities. We can win every game but also if we don't have determination and concentration, we can lose every game.

"We have to maintain a good behaviour in our work. We started the season believing we could win it.

"When I signed a contract with Chelsea, I believed we could win something."

Arsenal were guilty of not making the most of their chances in what was a typically competitive London derby.

Ashley Cole, who went off with a suspected hamstring muscle tear towards the end, received a hostile reception on his return to north London and Frank Lampard appeared to have a fake camera thrown at him while he was receiving treatment in the first half.

Both sides also had two players booked while John Obi Mikel was lucky to escape a second booking for remonstrating with referee Andre Marriner in the second half.

The leaders out-muscled Arsene Wenger's young side in all departments, but Ancelotti believes there is more to his team than their physical prowess.

"We have this quality of strength and when we have to use this, we can," the former AC Milan boss said.

"I think this team has a lot of technical, mental and physical quality.

"We didn't want to use physical quality, we wanted to use intelligence to defend in our half and there we won the game."

Drogba's double-strike moves him to joint top of the Premier League top scorers' list with 11 goals.

Ancelotti praised the 31-year-old's work-rate and also found time to applaud his strike partner Nicolas Anelka.

"Drogba scored two goals and for me he did a good job," said Ancelotti.

"In the second half he returned sometimes in defence in our half together with his other team-mates.

"Anelka in every game finds very good positions on the pitch. Sometimes he is a striker closer to the edge, sometimes he stays back a little bit to help the midfield keep possession. For this, he is a very important player for the team."