The Toon won 2-0 thanks to goals from Sandro Tonali and Bruno Guimaraes, with Nicolas Jackson seeing red for the visitors in the first-half.
However, Maresca insisted afterwards: "In this stadium against this team it’s already complicated, and if you give them one extra player it’s even more difficult.
"The red card affected the game, no doubt, but we had three big chances in the second half, which is not easy with ten men. The energy, the spirit and the togetherness of the team in the second half has been fantastic. It’s something I feel proud of."
We must win both games
The result leaves Chelsea in fifth place, two points outside the top four.
"Now my feeling is you need to win both games (to qualify for the Champions League).
"I didn’t speak to Nico, it’s not the moment. We will speak in the next day. No doubt he has to learn from it, especially at this stage of the season where we have two more games.
"You have to avoid this kind of thing. You need all your squad available. It happened, and he will be out. Hopefully he can learn for the future.
"He is our nine, the other one is Marc Guiu who has been injured for three months and is close to being back. We need to find a different solution for the last two games that are important."