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."