Step-mum Georgina Rodriguez was in attendance a week after it was announced by Italian media he had joined the 'Pulcini'.
Andrea Barzagli and Claudio Marchisio both have sons playing for the Juventus youth team as well.
'[Cristiano Jnr] is very competitive, he's like me when I was young,' Ronaldo said in an interview with DAZN via SportingNews.
'He doesn't like to lose and he will be like me, I'm sure, 100 per cent.
'I like to teach him some stuff, but he's going to be whatever he wants and I'm always going to support him.
'But of course I want Cristiano to be a football player, because I think he has that drive. He has a good body, he's fast, he has skills, he shoots good.
'But, as you know, he's going to take his decision and he's so young. I'm not going to put pressure on him, but of course I dream to see my boy a football player.'