Real visit tiny Eibar hoping to get their bid for a first league title since 2012 back on track after losing top spot to Barcelona following Wednesday's 3-3 draw with Las Palmas but Zidane said he would not risk his team's talisman.
"He (Ronaldo) felt something was not right and that's why he did not train today. Every game is important but the most important thing is that our players are ok, and so we'll wait and see what we do with Cristiano."
Ronaldo scored twice late on to salvage a point in a chaotic game against Las Palmas which saw Bale sent off for the first time in his Real career, earning the Wales forward a two-game ban to miss the fixtures with Eibar and Real Betis.
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Morata, who scored the winner in last week's 3-2 win at Villarreal, is also suspended against Eibar for accumulating yellow cards, meaning Zidane will look to Karim Benzema and Lucas Vazquez to lead his side's attack, while winger Marco Asensio could be in line for a return to the team.
"I have 24 players and the message has always been the same since I arrived: every player is important, if we want to win the league we can't drop many more points but as we play every three days we have to rotate our squad," Zidane said.
Real have dropped five points in their last three games, losing to Valencia and scraping a 3-2 win over Villarreal before drawing with Las Palmas.
Zidane admitted morale was low in the dressing room after the disappointing results but said there was no reason his team could not turn things around.
"I have noticed a bit of negativity, which you always get when you don't play well or get the result you wanted," he said.
"I'm used to that but for me the word crisis doesn't exist in Real Madrid or football because every three days you have the chance to do things better."
(Reporting by Richard Martin; Editing by Alison Williams)
