Idrissa Gueye lost his head in front of more than 70,000 people as he was sent off against Manchester United for slapping his own team-mate.
The Everton midfielder carelessly gave the ball away in the penalty area which Bruno Fernandes almost punished when his shot whistled just past the post.
As United players started jogging back to defend the goal-kick, Gueye confronted team-mate Michael Keane after the defender berated Gueye for his careless play.
The pair came face to face, with Keane appearing to move his head towards Gueye, before he raised his hand and struck Keane in the face with a slap, leading to a straight red card from referee Tony Harrington.