Di Matteo's side face the Citizens in the Community Shield on Sunday and the Italian has warned Roberto Mancini that his team will have many challenges to face this year.
"Everybody will be chasing them. They have a good squad, a good team," Di Matteo said. "When you're at the top, it's harder to stay at the top than get to the top. There'll be plenty of clubs trying to catch them up this season.
"The Premier League is getting more balanced every year. They have a good squad and will be difficult to catch, but that's the job of all the other teams: to try and win against City. The Community Shield doesn't give a big clue to what kind of season you'll have but it'll be a match both teams want to win."
Di Matteo has revealed that he will field a strong side at Wembley.