Madrid kept a clean sheet for the fifth straight game, recording a 2-0 win on Friday to move four points clear of rivals Barcelona with three games remaining.
Zidane lauded Courtois, who made four saves in Madrid's win as Karim Benzema netted a penalty before Marco Asensio's second-half goal.
"He has a very big influence. He is our goalkeeper, what he is doing every game is phenomenal," Madrid coach Zidane told a news conference, via AS.
"It is a matter for everyone when it comes to defending … today, he [Courtois] has been good for us with two or three stops, and then the strength of the entire team.
"We have to continue like this."
Madrid scored a penalty for the third straight game, while the VAR was needed to award Asensio's goal after it was initially ruled out due to an offside decision against Benzema.
🥅🧤🤳 @thibautcourtois: "Hello madridistas! We are very happy with the three points and the clean sheet, and we are already focused on Monday’s match. Hala Madrid!"#RMLiga | #HalaMadrid pic.twitter.com/fO1TZgeqp6— Real Madrid C.F. 🇬🇧🇺🇸 (@realmadriden) July 10, 2020
As another clean sheet helped Madrid, Zidane said he was happy with his team, who are away to Granada on Monday.
"I'm not worried because the important thing is to win matches," he said.
"We didn't score four or five goals, but because there is an opponent who defends. We scored two goals, one very beautiful in play.
"I am happy and calm with what we are doing."