Manchester United boss Sir Alex Ferguson admits signing Shinji Kagawa has influenced his introduction of a diamond formation.

The Japan international's versatility allows Ferguson do switch systems throughout games.

"The initial reason for signing Shinji Kagawa was his ability to play behind the strikers," Sir Alex explained.

"In the last couple of games he's played in the middle to the right of the diamond, which isn't a problem for him.

"He's still in a forward position, he still has the ability to create as he does from a central position.

"There's no big issue for me, particularly if we're playing the diamond formation because the central midfielders can all get forward and play in the central role."