Mancini raised eyebrows yesterday when he claimed Carlo Ancelotti's side were the best in England and would retain their title "easily".
It was a startling claim from someone who has spent more than £100million on his own squad this summer.
Yet even after Carlos Tevez had scored an excellent second-half winner to give City their third straight win against Chelsea after completing the double last term, Mancini did not change his view.
"I still think they will win it easily because I think they are the best team in the Premier League," he said.
"It is not possible for them to score five goals every game.
"Sometimes you might get a result like today. But they are the better team."
Tevez's 59th-minute solo effort was his fourth goal of the season, and his industrious performance on his own up front kept the Chelsea defence occupied in a tactical battle which City controlled largely due to the excellence of their own work at the back.
The South American charged forward after collecting Yaya Toure's short pass, jinked right and then drilled a precise shot through Ashley Cole's legs and in off the far post.
It was part of an overall contribution which showed exactly why Mancini made the surprising decision to hand the striker the captain's armband in preference to Kolo Toure this season.
"Carlos is a fantastic striker," said Mancini.
"Not only because he scored but because he fights all the time against tall players.
"At this moment we don't have all our players, so for him to be on his own is not easy for him."
Although City did not offer that much in attack, Mancini got his tactics spot on.
Nigel de Jong and Gareth Barry were outstanding in midfield, screening a defence that included 19-year-old Dedryck Boyata and Vincent Kompany, who completely outmuscled Didier Drogba.
"If Chelsea find space it is easy for them to score," said Mancini.
"But if they don't have space it is too hard and our players defended very well."
Mancini could not offer an explanation why City have now beaten Chelsea and Liverpool this season but failed to overcome Sunderland or Blackburn.
However, with Juventus to come in the Europa League on Thursday and then Newcastle next Sunday as part of three home matches in a row, the Italian is hoping to maintain the momentum.
"I hope the result will be important for us," he said.
"Today we can stay quiet. We can recover.
"But on Monday we must think about the next game in the Europa League. This result can help us to work harder and work well.
"We still have to get a lot of our players back.
"But we cannot think everything is OK just because we won this game."
Chelsea boss Carlo Ancelotti admitted City's midfield strength caused his side's first defeat of the season.
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."