Chelsea host the League Two outfit tomorrow night.
Maresca said: "It is dangerous because football is full of these kinds of games. In this moment, it is the worst game for us. It's better to have a different type of game.
"It's important but not because we think we're going to win this competition. It's an official game. We are going to try and prepare the game in the best way and try to win.
"We try to be focused on the things we can do better. The things we can control. We can be focused on the pitch side. It's the only thing we need to pay attention, how we can improve. We are progressing, in the right direction."
On being ahead of schedule, he added: "I said that we are ahead of where we expected to be today but not in terms of results; in terms of progression and how we are playing. In terms of results, we are far from City and Arsenal because we need to learn many things."