United were taken apart by Messi in the Rome final of 2009 and Maradona reckons man-marking him is pointless.
He said: "How should United play against him? There is no easy answer.
"If I was the coach of a team which was facing Messi and Barcelona, I wouldn't mark him one on one. Messi will lose his man. He drops deep into midfield and goes wide left or right. You can't afford to have a player who follows him because Barcelona will open space for others and they're a special team, not just one star player.