Chelsea won through goals from Malo Gusto, Joao Pedro and Pedro Neto.
Maresca said afterwards: "We are happy with the performance. I was very worried before the game because these are always tricky matches, but in the first half and second half, we created so many chances and didn’t concede anything.
"Even in the first half, I was happy with the performance, and the difference between the first and second halves is that in the second we scored goals and in the first we missed many chances.
"You need to be clinical, otherwise the game is always open and anything can happen. In the second half, we scored three goals, could’ve scored more."
On Gusto scoring a first goal for the club, Maresca joked: "Finally!
"Malo was close so many times and we like full-backs attacking and arriving inside the box.
"Last year, it (scoring goals) happened many times with Cucu (Marc Cucurella). Tonight, Malo scored to help the team because that goal opened up the game a little bit. So we are very happy for Malo."