Atleti were never in the contest but were just a goal down to the hosts after an hour had been played when Simeone chose to make changes.
With strike partner Luis Suarez also struggling for form and post-covid fitness, it was expected the Uruguayan would be replaced.
But to everyone's surprise, including Felix, he was unceremoniously subbed by Cholo with his team still very much in the game.
Just a minute later, Dani Carvajal's deflected shot cannoned off the post and off Jan Oblak before nestling in the net. And Felix made his feelings abundantly clear.
As the TV cameras panned around to the stands, Felix was seen shouting as he was handed a face mask, before lashing out with his boot towards the chair in the stand in front of him.
He then proceeded to sit with his head in his hands for much of the remainder of the game.
The 21-year-old has been enjoying his best spell in Spanish football of late, and his reaction to being replaced was typical of a young player confident in his ability to change a game.