Carlos Tevez's solo goal in the 59th minute at Eastlands ensured the champions' winning run came to an end in the sixth game of the new campaign.

Ancelotti's men had scored 21 goals and conceded only one in their opening five games, but this was seen as their first real test, and it was a test Chelsea were unable to pass.

Branislav Ivanovic hit the post for the visitors in the first half but City goalkeeper Joe Hart did not have a difficult save to make as the visitors time and again found City's midfield ranks, led by the excellent Nigel De Jong, impenetrable.

Ancelotti said: "We wanted to play better. As a team we didn't play well. We saw the power of Manchester City in midfield. We lost a lot of tackles and we were not able to play our football in the opponents' half.

"We played too complicated and gave the opportunity to them to take the ball and go on the counter-attack."

Chelsea remained leaders despite the setback, and Ancelotti refused to see the result in too negative a light.

"We are disappointed but we have to look forward," he said. "We are still top of the table. It was an important game, but every game is important. We did well five times then this time we lost.

"It is difficult to judge this team by one defeat. Our moment is very good, we are doing very well. It was not a good day but this team has a very good mentality."

Excellent though City were in cutting off Chelsea's attacks at source, the performances of his key forward players will have certainly disappointed Ancelotti.

Florent Malouda and Nicolas Anelka, who have scored 12 goals between them already this season, struggled to impose themselves on the game while Didier Drogba cut a frustrated figure before he was replaced by Daniel Sturridge with 15 minutes left.

Explaining the decision to withdraw Drogba, Ancelotti said: "I wanted to put more speed up front with Anelka and with Sturridge. He was fresh so I took that decision."

The victory was City's third in succession against Chelsea, after they completed the league double last season, and although Roberto Mancini has already written off his side's title chances, his opposite number is not so sure.

Ancelotti said: "It's not a good place for us. Manchester City are a very good team. They are growing quickly and will be an opponent for the title."

The build-up to the match was dominated by injuries, with City down to four fit defenders and Chelsea without the likes of Frank Lampard, Salomon Kalou and Yossi Benayoun.

Ancelotti gave a Premier League debut to 17-year-old midfielder Josh McEachran, who came off the bench for the final 10 minutes, and the manager insisted he is happy with the strength of his squad.

"I think we had on the bench considerable opportunity to change the players," Ancelotti said. "McEachran played only 10 minutes but he played well. You have to have confidence in your young players, and we do."