Manchester United boss Louis van Gaal was not happy with the decision that led to midfielder Juan Mata seeing red against West Bromwich Albion.
The 27-year-old Spaniard received two bookings inside three minutes with the Red Devils forced to play more than an hour with ten men.
And the Dutchman insisted referee Mike Dean should have been more lenient.
"What can I say when you send off a player like Mata?" van Gaal told BBC Sport.
"I have asked him if it's his first red card and he said yes. When you do that you give the first and second yellow within five minutes.
"You can do it according the rules but I think the referee has to know the person doing it. I don't think Mata has ever had bad tackles and something like that.
"You know the first one is a stupid yellow card and then you have to be aware the referee can give a second yellow card. A referee has to decide within one second but when you know the player, Mata never hurts a player.
"When you have to play 75 minutes with 10 players. I don't think we were so uncomfortable. We had several chances to score so it's always more difficult when you play 10 against 11. It's always very difficult for a team to play against 11.
"The loss is a big blow because it was not necessary. When you see the first half it was not necessary I think."