Ronaldo was given a Real Madrid shirt after Portugal’s goalless draw with Ukraine on Friday.
And the 34-year-old was amused by the incident, with footage showing him looking relaxed.
Ronaldo reportedly turned to the supporter in question and said: “Don’t you have Juventus?” The fan then replied by saying: “I have it, I have it.”
In the time since, the Portugal international has explained the reasons for his decision to leave – with Florentino Perez key.
“I felt it inside the club, especially from the president, that they no longer considered me the same way that they did in the start,” he said.
“The president looked at me through eyes that didn’t want to say the same thing, as if I was no longer indispensable to them, if you know what I mean.
“That’s what made me think about leaving.”