Chelsea boss Roberto di Matteo has played down their impressive start to the season.
He said: "We need to make up 25 points and I don't think any team has done that in the history of the Premier League.
"It's a big gap we have to fill. We will try our utmost and hopefully be able to compete.
"City haven't lost any key players and finished 25 points ahead of us last year.
"United had the same amount of points and they have signed Robin van Persie. I think they are still the two teams you need to beat."