Ramos revealed after Real's Club World Cup final win over San Lorenzo last month that he had played in the match despite a small thigh muscle tear.
The Spain centre-back has since trained alone and it remains to be seen if he will feature at the Mestalla.
Addressing the media on Saturday, Ancelotti refused to reveal whether Ramos will play, but insisted a cautious approach will be taken.
"He's in pretty good shape, he has trained alone and now he has to train with the team," said the Italian of Ramos.
"After training, we'll make a decision on whether he can play.
"It's a different situation to the Club World Cup, where he pushed himself to play because he wanted to.
"We have a lot of games after the Valencia match and if there are risks he won't play."
Real's clash with Valencia is the first of nine fixtures the European champions face over the next 35 days and Ancelotti believes rotation of players will be unavoidable.
"I think that it's essential. It allows us to avoid injuries and have a more motivated squad," added the coach.
"At this time in the season we need everyone, and we're not going to give more importance to Liga or the Copa [del Rey], we have to compete to the full in every competition.
"Against Valencia we'll field the best team possible, keeping in mind that there are a lot of games.
"Those who are in good shape and are not taking any risks will play. The priority is the match against Valencia."
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