Liga - Follow the Football match between SD Eibar and Real Madrid live with Eurosport.
Ronaldo has scored in his last seven appearances in all competitions, and Zidane said: "He is from another galaxy".
After securing a 5-2 aggregate victory over Paris Saint-Germain on Tuesday, Real swapped the Parc des Princes for the Ipurua Municipal Stadium, the smallest in La Liga with a capacity of just over 7,000.
It happens to the best of them, just ask Gary Lineker.
Ronaldo scored his 17th and 18th LaLiga goals of the season to ensure victory for Los Blancos at Eibar, but only four of the strikes came before the turn of the year.
Zinedine Zidane had insisted the success in Paris was now "forgotten" and his starting line-up suggested as much, with Karim Benzema the only key player rested.
However, when his French manager was asked about his player's absence following Cristiano Ronaldo's late victor, the former midfielder was only too happy to explain the somewhat vomiting-inducing reason behind it.
First, the unmarked Takashi Inui headed over from seven yards out and then Kike Garcia hit the side-netting with only Keylor Navas to beat.
Los Blancos struggled to get going in the first and they were dealt a blow on 28 minutes when Raphael Varane sustained a head injury.
Modric was excellent throughout, the Croatian providing a sublime pass with the outside of his foot for Ronaldo's opener.
The Spaniard had been at fault for Eibar´s equaliser earlier in the second half, allowing Ivan Ramis to head in an equaliser from a corner.
Ramos nodded the ball into the bottom corner after meeting Pedro Leon's corner.