As it stands, the Portuguese is due to miss the fixture against Villarreal next weekend after he was adjudged to have raised his hands to Bilbao defender Carlos Gurpegi.
However, the referee's official report, which suggests that Ronaldo directed a gesture to the fourth official, could land the FIFA Ballon d'Or winner a three-game suspension.
"In the 75th minute the player [seven] Dos Santos Aveiro, Cristiano Ronaldo, was sent off for the following reason: hitting an opponent in the face with his hand, while play was stopped," read the report.
"After having been sent off the No. 7 of Real Madrid, Cristiano Ronaldo Dos Santos Aveiro, while he was leaving the pitch, struck himself various times with the palm of his hand in the face, directing this to the fourth official."
It is believed that Madrid are preparing an appeal.