The 33-year-old was visibly distraught leaving the field after German referee Felix Brych, on the advice of his assistant, Marco Fritz, sent him off for an off-the-ball incident with Jeison Murillo, in which the Portuguese appeared to pull the Valencia defender's hair.
The five-time Champions League victor has been the top-scorer in the Champions League the past six seasons.
"If you're giving that as a red card, you can be sent off for any foul".
UEFA, Europe's football governing body, on Thursday stated that they have initiated a disciplinary case over Cristiano Ronaldo's controversial red card in the Champions League, and the case will be assessed on September 27, news agency AFP reported. The player will likely be available to face his former club Manchester United on October 23rd.
Despite his dismissal from the game, his Italian League outfit still went ahead to win the clash with Miralem Pjanic scoring twice from the spot.
He will find out next week whether his one-match ban is extended.
He is set to serve an automatic one-match suspension, which will rule him out of the home game against Young Boys on October 2.
"I just heard that he said it was because of hair pulling". The referee saw what he saw - not very well - and we overcame the obstacles.
Juve defender Leonardo Bonucci added: "Ronaldo was quite angry, unfortunately the referee did not see the situation very well". We're not women, we're playing football. "The important thing is we reacted as a team".