Chelsea may be seven points clear at the top with 13 games remaining but Nasri is convinced they could still be vulnerable.
The Frenchman said: “I’m a big fan of Mourinho, but I am not impressed with his team, not at all. We have played them twice, one time with 10 men, and we were better than them.
“Then we played them at the Bridge, we were better than them. When I have seen some of their games, I don’t think they are that fantastic – they are just strong and have a good striker up front.
“For me they are not special at all, and I think they are going to make some mistakes. We just have to perform, to win our games, and see what’s going to happen. This title will be like this until the end of the season. No-one will win the league 10 games before the end of the season.”
City famously overturned deficits to win both of their Premier League titles and Nasri said: “We know that the two times we won the league, we were behind at this time of the year.
“Two months ago we were eight points behind Chelsea and came back and went level with them. Now we are seven points behind, but are not going to make big talk about it. We will just try to get as many points as possible and wait for the mistake.
“The season is still long, they have the Champions League and the final of the Capital One Cup as well, so have a lot of games to play.”
The Frenchman has been embroiled in controversy at various times during his career, developing a reputation for making forthright comments, but he insists he is not about to change.
He said: “Sometimes it is better to shut up, but it’s something I cannot do. I managed when I was younger and I would sometimes come home with a lump in my stomach. Next, you explode but not at the right person.
“So I prefer to say what I think – even not being loved, even sounding arrogant. At least the people I love do not suffer.”