Chelsea boss Carlo Ancelotti says defending their Premiership crown will be even tougher this season.
Manchester United easily beat the Blues in the Community Shield last week while their neighbours City look strong after their summer spending spree to which Mario Balotelli was added last night.
"It will be more difficult to win the title this year," said Ancelotti.
"It is not enough to be like last year; we will need to work harder.
"Manchester United will be our biggest rivals.
"They have quality, tradition and history but I know that we have to pay attention to the other teams.
"Arsenal bought a fantastic striker in (Marouane) Chamakh, Liverpool have a new manager, they could be a strong opponent, and we have to look at Manchester City because they bought a lot of good players and they have to build a team. They could be involved in the title race."
