A brace by former Marseille star Samir Nasri handed Arsenal the win.
United managed to hit one back at the early stages with a wonderful goal by whizkid Rafael da Silva, who came on as a sub for Gary Neville who had a poor matches.
Wayne Rooney, Cristiano Ronaldo and Dimitar Berbatov did all miss their chances in front of goal in a match United should at least have managed to get a draw.