Reyes replaced Simao on 63 minutes and entered the field to a chorus of negative chants and booing from the Vicente Calderon crowd.
The former Arsenal and Real Madrid attacker has been forced to deny rowing with coach Javier Aguirre in the last week and also his agent has admitted he is likely to leave if the situation doesn't change.
After the game, Aguirre said: "He showed good mental strength. He kept calling for the ball and trying. The boos were becoming less and less by the end of the game."