Joao Felix (2), Mykhaylo Mudryk and Christopher Nkunku struck the goals for the visitors on the night.
Maresca later said, "It was a very good performance. I think we struggled a little bit at the beginning of the game. And we adjusted; we struggled off the ball with our pressing, I think on the ball we were quite good - and then we made some adjustment and were much better.
"The most important thing, I always said, no matter how many players we change, you can see the identity of the team. We can do things better. The identity is quite clear, the way we play on the ball and the way we play off the ball.
"It was a very good performance. I think we struggled a little bit at the beginning of the game. And we adjusted; we struggled off the ball with our pressing, I think on the ball we were quite good - and then we made some adjustment and were much better.
"The most important thing, I always said, no matter how many players we change, you can see the identity of the team. We can do things better. The identity is quite clear, the way we play on the ball and the way we play off the ball."
Maresca also insists they shouldn't turn up their nose playing in the competition.
He also said, "It's because last year, we qualified for the Europa League and then we play Conference. If we play Conference, then it's because in this moment we belong to the Conference. If next year or two years we play Champions League, then it is because we deserve to play Champions League.
"I think football always puts you where you deserve to be. If we play Conference then it's because we deserve it. The first target for us is the group stage and then we will go game by game and we will see. The important thing now is to finish the group stage well and qualify for the next round."