Manchester United team-mate Rio Ferdinand has attempted to explain just why it meant so much to the 33-year-old.
Ronaldo was shown a straight red for an off-the-ball incident against Valencia in the first half of the Champions League clash.
The forward clashed with Jeison Murillo, appearing to kick out at the defender before tugging at his hair.
The referee consulted with his assistant behind the goal before calling Ronaldo over and brandishing a red card, much to the five-time Ballon d’Or winner’s disbelief.
Ronaldo, who has scored 121 goals in the competition, protested his innocence and burst into tears as headed for the touch line.
He will at least miss the home game against Young Boys but could be forced to sit out the double-header against United if he is banned for three games.
And Ferdinand reckons this is one of the main reasons behind his tears.
“I don’t know. I think it [the red card] is inconclusive really, it’s hard to see,” he said on BT Sport.
“I’m sure that Cristiano Ronaldo and Juventus will appeal that.
“I think the emotion you can see coming out here, I think he’s going back to Old Trafford – he’ll miss that game – he wants to play football, you can see that.”
Juventus are likely to appeal the decision with the player automatically handed a one-match ban.
According to the UEFA guidelines: “As a rule, a player who is sent off the field of play is suspended for the next match in a UEFA club competition (i.e. UEFA Champions League, UEFA Europa League or UEFA Super Cup).
“In case of serious offences, the UEFA Control, Ethics and Disciplinary Body is entitled to augment this punishment, including by extending it to other competitions.”