The Portugal international gave Madrid a 12th-minute lead at Santiago Bernabeu as he collected Karim Benzema's left-wing cross and fired home.
Benzema and Ronaldo then reversed roles as the Frenchman doubled Madrid's lead, before the former Manchester United man scored a penalty to leave Ancelotti in awe of his current form.
"Right now, Cristiano is out of this world," the 54-year-old told reporters.
"He is playing with incredible consistency and scores a lot of goals. It's difficult to find the words to describe him."
Ancelotti also praised the players who are finding themselves rotated most weeks, adding: "A team has to play in a way to use all the characteristics of its players.
"Khedira has enough quality to play for Real Madrid. He is consistent and always helps the team.
"Xabi Alonso has a lot of experience and quality to help us play the way we want to play; I've said it many times.
"There are important players on the bench such as [Angel] Di Maria and Isco. We have many options in midfield."