The Portugal international found the net twice at the Bernabeu on Wednesday evening to ease some of the early-season pressure that had been building on his side.
Los Blancos, without their star talisman domestically due to a five-match ban, have drawn their last two home league games to give Barcelona a headstart in the La Liga title race.
Zidane is pleased with the way his side responded in their first European match of the campaign, though, while also reserving special praise for Ronaldo, who now has a record 107 goals in the competition.
"He's the best in the world," he told beIN Sports after the game. "He's always there, he always scores. If he was luckier today, he could have scored four. We know the ability that Cristiano has.
"We are happy. There are no quiet games. APOEL have experienced players and are not overwhelmed by the Bernabeu; they just went out and played. If you're not focused, they can hurt you."
Madrid, four points adrift of Barcelona after three league games, return to action on Sunday when they travel to Real Sociedad.