Everton boss Marco Silva slammed the referees for allowing Arsenal's second goal on Sunday.
Pierre-Emerick Aubameyang converted Aaron Ramsey's flick to make it 2-0 to the Gunners. The Gabon international was offside but referees allowed the goal to stand.
And speaking after the loss, Silva was frustrated with the goal.
"It was offside. At this level, with these mistakes from the referee, it put our team in that condition as well," he said.
"The second goal is clearly offside. It is really frustrating, and I tell you why. In that moment we had just one player in our box, it is too clear for the assistant.
"It was two or three against one, just Jonjoe Kenny inside the box. It is clear where he is, and where the player who scored is.
"It is clearly offside. For me it is a little bit strange, but OK, mistakes are made, I make them as well, and the assistant and ref they can make them as well."