Espanyol went ahead through a Thibaut Courtois own goal before Real fought back via Dani Carvajal, Vini Jr, Rodrygo and a Kylian Mbappe penalty.
Ancelotti later said: “It was a good game. We started really strongly and then reacted well to Espanyol's goal. It was a complete performance and we played much better, with a nicer pace and creating more chances. I'm really pleased. We had a lot of the ball in the first half because the opposition defence was sitting so deep. We did a good job. The second half was really good for us because the game opened up and became a bit of a rock and roll clash.
"We played much quicker up top, moving the ball faster and being smarter off it. We don't have a centre-forward who holds his position but Rodrygo got in there really well for the second goal, just like Bellingham often does. Being mobile is a big weapon. The third goal was fantastic too. These are resources we must have. We won the ball back really well and pressed pretty well whenever we lost it. We created a lot of chances and we're happy. We're gradually approaching our best.
"We've gone 38 games unbeaten in LaLiga and that's a fantastic statistic that underlines how well this team have played, are playing and will continue to play.”
On Carvajal and Jude Bellingham injuries, he added: “Carvajal took a knock. It was a kick, nothing too serious. Bellingham has problems with his shoulder, they sorted him out and he was able to play without any issue. It doesn't look too worrying but we'll have to see how his shoulder responds tomorrow. He's always been playing with protection but he's stopped using it this season. The problem has resurfaced but he didn't ask to come off and I don't think it's a big thing. He'll have to look after himself but I think he'll be available for the next game."