Watford manager Javi Gracia was left scratching his head as to 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.
Foster dawdled with the ball after a back pass from Daryl Janmaat, allowing Aubameyang to close him down and deflect the goalkeeper's clearance into the back of the net.
That 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 Spaniard'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.
"It's true they got the points but for us, my opinion, we had a good performances, because with 10 players we created some chances and dominated the game. For me, this is good news."
Arsenal manager Unai Emery adopted a stance his predecessor Arsene Wenger was famous for, claiming not to see Deeney's red card, 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.
"But we didn't do all we wanted to do. But we can be happy with the result because coming here is tough.
"The result gave us the opportunity to continue on our way and be consistent in the table.
"The three points is the most important today but we worked at being consistent in our structure, in defending the long ball and set-pieces because they are a very strong team doing that.
"With the ball I wanted to do better, we didn't do that but in some moments we had chances for the second goal but we couldn't take them."
