Avram Grant has voiced his disappointment at the Football Association's decision to reject Chelsea's appeal against John Obi Mikel's red card.
Mikel was sent off by referee Mike Dean during Chelsea's 2-0 defeat at Old Trafford on Sunday for a challenge on Patrice Evra.
The Nigerian midfielder is set to serve a three-match suspension after the FA's disciplinary commission upheld Dean's original decision.
Grant has expressed his frustration at the decision, reaffirming his belief that Dean made a mistake in showing Mikel a red card.
"I am very disappointed and surprised. One of things I teach my players and even my children is that when you make a mistake you can admit it," he said.
"I can promise if I make a mistake I will tell you. It has happened to all of us - nobody is perfect.
"The referee made a mistake - he made three mistakes - but one of them he could correct and he didn't do it, so I am very disappointed.
"On Sunday, the referee affected the result with three bad decisions. Our players were very disappointed but I like their reaction. If I saw something wrong, it was the decisions of the referee."