Liverpool boss Kenny Dalglish wants his players to get in the faces of Manchester United tomorrow.
Dalglish will urge his players to be competitive but controlled against Sir Alex Ferguson's side, who have had their own recent discipline problems with Wayne Rooney escaping punishment for an unprovoked elbow on Wigan's James McCarthy last weekend and Nemanja Vidic suspended for Sunday's game after being sent off against Chelsea.
"It's hard for us to talk about discipline when we got somebody sent off in the last game but I don't think it's difficult to be disciplined," said the Reds boss.
"You have to compete and it's a fine line as to how you do that.
"If you do something stupid you deserve to be sent off. I don't think there is a problem with discipline from either team - certainly from us there is no problem.
"You've got to have controlled aggression, not just for this game but for any game.
"You can't go around punching and kicking and headbutting people and expect to stay on the pitch.
"It's got to be within the rules of the game. The lads know the rules but they also know we've got to compete."
