Aston Villa boss Martin O’Neill declared himself disappointed with referee Phil Dowd after United overcame his side to retain the Carling Cup.
O’Neill felt Nemanja Vidic should have been dismissed for his foul on Gabriel Agbonlahor which led to James Milner opening the scoring from the penalty spot.
He believes that the Reds would have been at a much greater disadvantage in the game and perhaps would not have gone on to score the two goals that won the match.
“I think it would be universally accepted they should be down to 10 men. There's no other decision to make,” O’Neill told BBC Sport.
“It's not a good decision by an otherwise fine referee. It's poor and obviously if he gets it right we score the penalty, they are down to 10 men for virtually the whole game. It's a major point in the game.”
The player in question took a different view on the situation, stating that he didn’t believe the foul was worthy of a sending off.
Vidic said: “I didn’t really think about it, I was just disappointed at how I reacted in the situation. I expected a yellow card.
“I knew it was a penalty and I was annoyed with myself but I didn’t expect a red card to be honest.”
United were reduced to ten men in the previous meeting with Villa, in the league on 10 February. On that occasion, Nani was sent off but the Reds managed to draw 1-1 and were, in many people's eyes, the team more likely to win.