The striker stepped up in the absence of suspended team-mate Cristiano Ronaldo by scoring a double, alongside goals from James Rodriguez and Sergio Ramos, to shake off early nerves that had seen David Moyes' men take a shock lead in the first minute.
"Benzema played a fantastic match," Ancelotti told reporters. "Like all our strikers, he has a lot of quality and is very effective.
"We have finished many games now with him on the scoresheet. The goals he has netted today were quality.
"He is a striker who has a great shot on him. He is not a striker who lingers on the penalty spot, but meanders around the area."
The Italian coach showed signs of irritation, however, when asked about Gareth Bale's contribution on the match, with sections of the Spanish media seemingly desperate to focus on the moments in the game where it did not go right for the Welshman as he missed an open goal but also picked up an assist.
"I want no more negative talk about him, he did very well today," Ancelotti added. "It is true that he missed two chances to score, but he made the assist for Benzema's first goal, for instance. He works well with his colleagues."
The European champions' victory ensures that they will at the very least maintain their one-point (with one game in hand) advantage over second-placed Barcelona in La Liga.
