The Portuguese has been struggling with a hamstring injury of late, while the French forward was forced off with a groin problem last weekend
Ronaldo looked set to make his return from a hamstring problem sustained against Valladolid on May 7 in last weekend's Liga clash with Espanyol.
However, he was forced to pull out of the game after experiencing some discomfort in his thigh during the warm-up, while Benzema was forced off injured 67 minutes into the game at the Santiago Bernabeu.
Ancelotti, though, fully expects the pair to be available to face Atletico in Lisbon this weekend.
"I believe that both will play," he told reporters on Monday. "The two of them are fine."
Saturday's Madrid derby is scheduled to kick off at 20:45CET.