Watford manager Javi Gracia was left scratching his head over why referee Craig Pawson sent Troy Deeney off in the 1-0 defeat to Arsenal.
The Hornets captain saw red in the 11th minute at Vicarage Road after challenging Lucas Torreira off the ball, completing a horrible two minutes for the hosts, who had just conceded after a shocking error from Ben Foster allowed Pierre-Emerick Aubameyang to score.
That goal proved enough for the Gunners, who moved back into the Premier League top four after a first away clean sheet this season.
Pawson's decision was made with assistance from the linesman and replays showed Deeney's forearm making contact with the Uruguay international’s face.
Nevertheless, Gracia was left surprised to see the official brandish the red card.
"I don't agree, but I respect the referee's decision," Gracia said. "It is maybe a yellow card, but red card? I don't understand why the referee did it.
"I prefer not to speak only about that. He (Deeney) hasn't got to explain anything to me, I could see the play and I could see the contact with his arm but never with his elbow.
"What can I say? I don't understand the decision but we respect it. We tried to look for the resolution.
"There is a contact but it is not with his elbow, it is with his arm or hand, I don't know which part exactly.
"I never saw an aggressive movement. I don't understand why the referee took that decision."
Despite the fact they played with a man less for almost 80 minutes Watford put on a fine display and were unlucky not to take at least a point.
They hit the woodwork twice, through Craig Cathcart and Adam Masina, while Gunners goalkeeper Bernd Leno made a number of decent saves.
"We have competed really well with 10 players and today my players don't deserve to only speak about the result," Gracia added.
Arsenal manager Unai Emery adopted a stance his predecessor Arsene Wenger was famous for, claiming not to have seen the incident that led to Deeney's dismissal, nor did he divulge what Deeney said to him on his way back to the dressing room.
Emery said: "He said something to me, I can't say, because I don't know. I answered him, I don't know.
"I didn't see and I respect the decision from the referee. It is clear it helped us, with this decision because to play with one less player for them was more difficult.
"But our goal gave us the advantage and helped us to take more control of the game."