Sources tell AS the club is angry, not just for the Juventus player's gesture at the end of the game, similar to Simeone's in the first leg but directed at the away fans.
Atlético de Madrid are still furious with Cristiano Ronaldo for the attitude he showed on the final whistle of this week's Champions League return leg in Turin.
The Juventus striker, who turned the tie around with a hat trick in the second leg, turned to the stands where Juventus and Atlético fans were seated and made an obscene gesture - a more exaggerated version of Diego Simeone celebration during the first leg at the Wanda Metropolitano (the Atleti coach simulated holding his genitals and was served a 20,000 euro fine by UEFA for improper conduct).
The difference between the two gestures is that Simeone's was directed at Atlético's own supporters, which he himself stressed after the game whereas Cristiano's was aimed at the travelling supporters.
To make matters worse, Movistar Liga de Campeones cameras caught the Juve player taunting Atleti fans by calling them 'motherf***ers' (hijos de puta) just before he scored the third goal - the images were later broadcast in Spain by #Vamos.
Atlético de Madrid were not happy with the insults to their fans or the gesture and AS understands that the club are considering presenting a formal complaint to UEFA.
If UEFA open a case against Cristiano, he could be served an economic fine similar to the one Simeone was given and possibly be hit with a suspension (from one to three games) if UEFA decide that Cristiano's behaviour could be construed as inciting violence.