Christopher Nkunku and Mykhaylo Mudryk struck for the Blues.
Maresca said afterwards: "Yes, tough, very tough. This is exactly the way we expected the game, against this team away. Small pitch, it's always complicated but overall I think we did very well.
"We could have scored more goals but we also conceded some chances. Overall, I think we deserved to win the game and I'm very happy for the players."
"It was a very good challenge for all the aspects. They were high pressing, they were intense, but no matter what the opposition do, it is important we are ready. It's important also to continue with that mentality; to try and win all the games."
Asked about goalkeeper Filip Jorgensen and goalscorer Christopher Nkunku, Maresca also said: "Both did very well. They did fantastic. I think all of them. Jadon Sancho did a very good game. Axel (Disasi) and Benoit (Badiashile), Cesare (Casadei) did very well. It is important they are ready when they get the chance.
"Filip did a very good game, Christo the same. We have a game on Sunday and then on Wednesday. We have nine or 10 games in December, so it is more or less a game every two or three days. They are going to get chances so they need to be ready."