The holders have a 3-0 aggregate lead over Juventus ahead of Wednesday's quarter-final second leg at the Santiago Bernabeu.
Ronaldo's brace inspired victory in Turin, with his second – a stunning overhead kick – prompting applause on all sides of the stadium.
Already Madrid's all-time leading goalscorer, club president Florentino Perez told Gazzetta dello Sport he believes Ronaldo is the heir to the great Alfredo Di Stefano.
It is lofty praise indeed, with De Stefano an undisputed legend at the 12-time European champions, and Zidane added his own voice to the chorus.
"I don't envisage Real Madrid playing without Ronaldo. We are delighted with his achievements," he said.
"Many people talk about Di Stefano and there are lots of people who will remember Ronaldo's passing through this club, me included.
"We've got to enjoy these moments – I'm sure Real Madrid fans more than fans from opposing teams, but it's amazing to experience this along with Ronaldo."
Zidane was a little more reticent when he once again bristled at the notion of Madrid being labelled favourites to win Europe's top competition for a third consecutive season.
"We prefer to leave the talking to the pitch," said the Frenchman. "If you ask me, I reply and my answer is I do not want to sit here and answer that question.
"We have to respect all the teams. We have to respect the sport too.
"The other day, against Atletico Madrid [Sunday's 1-1 draw, where Madrid led through Ronaldo] we could have lost. That's football. One attack and everything goes to waste.
"You have to respect the big teams and they never give up or roll over."
Sergio Ramos and Nacho are ruled out of the second leg by suspension and injury respectively, leaving Raphael Varane as Zidane's only fit first-team centre-back.
Holding midfielder Casemiro could drop back to partner the France international, while the inexperienced Jesus Vallejo has overcome a muscle injury to be in contention.
"I don’t think Varane needs to do anything special, anything different from what he normally does," added Zidane.
"This is a team, we need to continue playing well as a team and Varane needs to keep doing what he's doing. He's playing at a very high standard – nothing different
"He respects his team-mates, he respects his opponents and hopefully he can stay here for the rest of his career."