The Portugal captain has been absent for Real's last three games due to knee and thigh problems, and it has been suggested that he will miss Wednesday's final against Barcelona and the UEFA Champions League last-four first leg with Bayern Munich next week.
Real are hoping to complete the first leg of a potential treble of Liga, Copa and Champions League in Valencia this week, and Ancelotti has insisted his side still have a great chance of beating Barca - even if Ronaldo, who has scored 45 goals this term, cannot play.
"He's (Ronaldo) progressing every day so don't rule him out," the Italian told El Mundo.
"But we won't take any chances.
"If he doesn't play then the system won't change. The players are confident and comfortable.
"They have faith in the system and they're doing well."
