The Portugal star, who won his fifth Ballon d'Or this week to draw level with Lionel Messi in the all-time standings, was inspirational to his side's demolition of the visitors in the first half at the Santiago Bernabeu.
Ronaldo scored twice and was otherwise a menace to Eduardo Berizzo's side as Madrid scored all five goals before half-time, with Nacho Fernandez, Toni Kroos and Achraf Hakimi also on the scoresheet.
Zidane has defended Ronaldo's performances this season during a relative goal drought in La Liga, and he believes the 32-year-old's showing vindicated his support.
"It could be this is his perfect week and I hope he continues in this rhythm," he told a news conference.
"I already said – I didn't say it for nothing – because I know him and I know his ambition every day in training, I knew he was going to score.
"Sometimes he doesn't and nobody is happy, but you always have to be careful with him."
Zidane hopes to see Madrid keep up this standard of performance as they prepare for the Club World Cup and the Clasico on December 23, although he is not convinced their first-half showing on Saturday was their best of the season.
"Hopefully we can keep on scoring, that's two games and eight goals and we have to continue like this," he said, with Madrid having also beaten Dortmund 3-2 in the Champions League this week.
"We're growing in every aspect. We're happy, we did really well and it was important to help us prepare for the game on Wednesday. There's no easy match but it's better to travel with this result.
"I don't think it was our best 45 minutes but, with goals, yes it was. On a playing level, I think we've had some good games, against Real [Sociedad] and Dortmund in the Champions League, for example.
"It's a good feeling; we scored five goals against a team it's not easy to play. To keep a clean sheet and score five, we're happy, but it's not the best."
The European champions now turn their attention to the semi-final of the Club World Cup next week, with a match against Al-Jazira to come on Wednesday.
Zidane offered some good news ahead of the game in Abu Dhabi, suggesting Raphael Varane and Gareth Bale could both be fit enough to play a part.
"They're going to travel with us. It's day-to-day out there," he added. "On Tuesday, I think they'll train normally and we'll see what we can do with them."