Aston Villa keeper Brad Friedel insisted Phil Dowd's failure to send off Manchester United defender Nemanja Vidic was crucial in deciding the final outcome of the Carling Cup final.
Vidic was the last defender when he hauled down Villa striker Gabriel Agbonlahor inside four minutes.
Referee Dowd awarded a penalty - converted by James Milner - but no further action was taken against Vidic and United recovered to win 2-1 with goals from Michael Owen and Wayne Rooney.
But Friedel is convinced the heavy pitch would have taken its toll on United had they had to play virtually the whole game with 10 men.
Friedel said: "We started the game really well but we have seen the penalty incident now and it really should have been a sending-off.
"You feel really hard done by after you have viewed it afterwards because you would have liked to be playing against 10 men.
"We feel a bit hard done by that we didn't play with a man advantage after that, especially on a pitch as heavy as that and cutting up like that.
"With 10 men, they would have really tired towards the end but it wasn't to be."
Villa defender Carlos Cuellar echoed Friedel's sentiments and said: "For me it is a penalty and a sending-off. I think everyone says the same.
"You saw the sending-off of (Juliano) Belletti of Chelsea for something similar on Saturday. I think this was even more clear.
"But different referees make different decisions and you never know what would have happened had we had the extra man."
Midfielder James Milner admitted producing a decent performance was no consolation for Martin O'Neill's team.
He said: "We didn't play too badly but that is not what it is about and, in finals, it is about getting a result and winning the game.
"We came up against an experienced side who have played in a lot of finals and maybe that told in the end.
"But I don't think we did ourselves any harm. We put in a good performance, had chances."