Earlier, Barcelona shrugged off the absence of the injured Lionel Messi to move to within a point of Madrid at the top of the table as Luis Suarez and Neymar were on target in a 5-0 thrashing of Sporting Gijon.
Yesterday, Ronaldo was replaced moments after helping Madrid go 2-1 in front when Karim Benzema slotted home the rebound after the Portuguese's initial effort was saved.
However, he watched on as Sergio Araujo took advantage of some soft Madrid defending to level as the European champions dropped points for the second time in four days.
"We have another game on Tuesday and he has to rest too now and again," Zidane told Spanish TV station Movistar.
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"It is obvious he always wants to stay on the field, but I have to think about my players and particularly Cristiano.
"I have to take him off sometimes and tonight we did it."
Stung by a poor first-half performance in a 1-1 draw with Villarreal in midweek that snapped a 16-game La Liga winning streak, Madrid pressed high from the off and had 17 shots in a wide open first 45 minutes.
The lead lasted just five minutes, though, as Raphael Varane's poor defensive header fell at the feet of Tana, who slotted past the helpless Kiko Casilla.
Varas denied Ronaldo midway through the second half, but substitute Benzema was on hand to turn home the loose ball.
Ronaldo was then replaced by Lucas Vazquez, but didn't acknowledge Zidane as he sulked off the field.
And Ronaldo's mood worsened when Araujo bundled his way
- Suarez magic -
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Earlier, Barca overcame a difficult opening half hour to hit five past 10-man Sporting.
Yet, Barca coach Luis Enrique was far from satisfied with his side's display, particularly early in the second half.
"It is a result that doesn't tell the true story of the game -- 5-0 makes it seem easy and simple and that couldn't be further from the truth," he said.
"We were poor at the start of the second half, we didn't kill the game off and Sporting could have got back into the game."
A fine team goal put the game beyond Sporting moments later as Neymar freed Sergi Roberto down the right and Rafinha met his cross with a powerful near-post header.
More goals flowed in the final 10 minutes after Alberto Lora dived in on Roberto to leave his side a man light.
Paco Alcacer was denied his first Barca goal when he smashed the ball off the underside of the bar, but Neymar mopped up the rebound to make it 3-0.
Denis Suarez then teed up Neymar to sweep home his second of the game two minutes from time.
Sevilla missed the chance to go level with Madrid at the top as they suffered their first league defeat of the season, losing 3-1 at Athletic Bilbao.
On-loan Manchester City midfielder Samir Nasri's first Sevilla goal was in vein as Mikel San Jose, Mikel Balenziaga and Aritz Aduriz's injury time penalty lifted the Basques up to third with a fourth straight win.