Reports in Spain suggested the Portugal international had been playing through the pain barrier recently as Real slipped off the pace in La Liga.
Ronaldo was unable to prevent defeats against Barcelona and Sevilla this week - with Real falling three points behind leaders Atletico Madrid in third place.
However, Ancelotti dismissed any notion that Ronaldo could miss games in the title run-in due to the problem, stating he will play against Rayo Vallecano on Saturday.
"Cristiano has trained normally. He will play (on Saturday). He doesn't have any problems," Ancelotti said.
"Cristiano has a little issue, but it doesn't stop him from training normally.
"If things get worse naturally Ronaldo would rest but everyone is relaxed at the moment."
Real's back-to-back defeats leave them with plenty of work to do in their title quest and Ancelotti's men play after both Barcelona and Atletico on Saturday.
However, such is the close nature of the race for the Spanish top flight, Real could find themselves back top by the end of the weekend if results go their way.
In terms of their own performance, Ancelotti has called for an improved defensive effort.
"We have to be more focused than we normally are," he added.
"It's clear that we have become weaker in defence. We made small mistakes that have cost us many goals.
"I don't know how many points are needed to win the league, but it will be decided in the last match.
"The league will be won with more than 90 points for sure."
