Wayne Rooney has admitted that there is no place for "second best" at Old Trafford and he has acknowledged that he needs to work hard to maintain his fitness.

Rooney came under fire from his manager Sir Alex Ferguson regarding his fitness after a below-par display in United's opening match against Everton, and the England striker acknowledges that he needs to work hard to avoid being dropped from the side.

Rooney told The Mirror, who are serialising his autobiography: "As a striker, I need to work hard all of the time. I need to be sharp, which means my fitness has to be right to play well. If it isn't, it shows.

"As a centre-forward at Manchester United, there is no place to hide. I've got to work as hard as I can, otherwise the manager will haul me off the pitch or drop me from the next game.

"There is no room for failure or second best at this club."

Rooney is currently out injured with a gashed thigh, but he could return by the end of September.