Portuguese superstar Ronaldo was facing the possibility of missing Saturday's contest at the Santiago Bernabeu after he was harshly booked for simulation in Wednesday's 2-0 victory at Rayo Vallecano.
That left him facing a one-match ban after accumulating five cautions, but the Spanish Football Federation rescinded the caution on Friday, with Ronaldo appearing to have been fouled by Antonio Amaya.
Head coach Ancelotti confirmed that fellow forward Bale will miss out in order to be fully fit for Real's UEFA Champions League first leg clash at city rivals Atletico Madrid on Tuesday.
And with James Rodriguez and Toni Kroos suspended against Eibar, Ancelotti said it was an easy decision to appeal Ronaldo's booking.
"Bale isn't available for Eibar. He had a scan which is normal, but he has a slight knock so it's better to rest him to prepare him for Tuesday," he explained.
It was put to Ancelotti that it may have made sense not to appeal Ronaldo's yellow and allow him to serve a suspension against Eibar, rather than risk missing a match against more high-profile opponents if he should acquire a fifth yellow later down the line.
But the Italian stated that it was vital to have his talisman available, adding: "We thought it wasn't a fair booking, which is why we appealed it.
"Also for the game tomorrow we need Cristiano. We have an important game, we have a lot of respect for Eibar.
"We can't fail so we have to use the best team possible and that's why the appeal for Cristiano's card was normal because it wasn't fair."
Ancelotti also confirmed that Luka Modric has been cleared to play despite being seen clutching his left thigh after the Vallecano victory, while centre-back Pepe is also fit following a thigh injury.
