He said: "There's no trick to beating United. You just have to work hard.
"You know when you meet teams like this you have to have legs, track them down and not let them play football.
"If you let players like Cesc Fabregas at Arsenal and Ronaldo have the ball . . . they are too good. You have to be aggressive and keep the team very compact.
"That is the secret - but keep it a secret, OK!"