Manchester United boss Sir Alex Ferguson admits Chelsea's start to the season has him concerned.
He said: "If you go back to when Chelsea won two titles in a row, they got off to fantastic starts straightaway. We were playing catch-up and had to do something about it. The following season we changed our training to ensure we got a good start. In my time we've always geared training to be good in the second half of the season. Today, I don't think you're afforded that luxury.
"You see Chelsea's start this year, with a new coach and new ambition - they're top of the league on maximum points. You may think three points is nothing, but I think it is something. City are the same, they've won all their games. So it's a really difficult league and we don't want to be playing catch-up."
