He told the London Evening Standard: "At Chelsea, it would be my greatest achievement if we beat them to the title this year. We were champions before but we were the team to be champions, to attack the title, especially in our second season when we killed it from day one.
"This is a team in development and if you win titles in this time, it is not handed to you. It would be a super achievement. But we are not worried about that right now, just thinking about improving every day.
"City, in terms of power of the squad, are in another dimension. You can't compare their situation with any other club. Some people disagree or some managers feel they shouldn't say it but I say what I feel. City are different.
"It's not about having quality players, other clubs also have quality. But Man City are in the perfect moment. They don't have old players or young players - the only young player is Matija Nastasic and he plays sometimes. After that all of them are between 25 and 29, everyone in the best moment.
"The number of players they have at the same level is amazing. The physicality adapted to the Premier League is amazing. They have a couple of players that are smaller and very talented but they have a number in the team that are big physically.
"They have four strikers, all of them are top class and the one on the pitch is always scoring."