The Spanish giants renewed hostilities at the Santiago Bernabeu and Neymar gave the visitors a dream start by firing the Catalans ahead after just three minutes.
It was the Frenchman's sixth goal in his last four outings, and Ancelotti has claimed that his star striker is "on fire".
"I value the effort of the team. We didn't lose our heads after Neymar's goal and all went well," he told reporters.
"Isco's performance was impressive but today we could talk about Benzema, Isco, Cristiano or James [Rodriguez]. It's hard to talk about a star in this match but Benzema is on fire."
The win ended Barcelona's eight-game unbeaten run in La Liga, but they remain top by a point.