Chelsea boss Ancelotti: Race for title even tighter this season
"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."