Portsmouth boss Harry Redknapp has singled out Sulley Muntari for criticism after Sunday's 3-1 defeat by Everton.
"It's no surprise he does that. We worked on it before the game. So for Sulley Muntari to track him halfway and then switch off was frustrating. We had a dreadful start, got back into the game and did that.
"We have to work on it because if we think that was tough just wait until Saturday. That's going to be even tougher. Everton are a strong team but United are on another level."