Unbeaten but underwhelming, Manchester City's stuttering start to its Premier League title defense is already causing anxiety at the club.

After winning only two of the opening five league matches, Robert Mancini's defensively deficient team is four points behind leader Chelsea.

And it's not only in the league where City is struggling, with a loss in the Champions League at Real Madrid last week followed Tuesday by an early exit from the League Cup.

Preparing for Saturday's match at Fulham, City defender Maicon says ''we have to improve quickly because we can't afford to have any more distance between us and the teams at the top of the league.''

Chelsea faces its first real test of the season Saturday with a London derby at fifth-place Arsenal.