The Argentine goalkeeper will make his second appearance for City, having impressed the manager with his performances and contribution behind the scenes.
"He's good. Before I arrived here, I had a conversation with him, he knows his role and that's important," Maresca said.
"Day by day he is helping a lot. When he has played, he was good and tomorrow he will play again."
City are also expected to rotate their squad after suffering a 2-1 Premier League defeat at Aston Villa last weekend.
Maresca revealed that Erling Haaland, Elliot Anderson, Gianluigi Donnarumma, Josko Gvardiol and captain Ruben Dias had each been given three days off to recover.
"After Villa, we gave five players three days off. Erling, Elliot, Gigio, Ruben and Josko. Go away on holiday. Three days off, go, come back. Full energy," he said.
With Wednesday's cup tie followed by another meeting with Brighton at the Etihad Stadium in the Premier League on Saturday, Maresca admitted that changes were necessary.
"In terms of how we plan, they (the games) are so close so we need to make some changes," he said. "We have one more session and then we decide for tomorrow."
Brighton arrive in Manchester in impressive form, having earned praise for their attacking football and scored more goals than any other team in the Premier League this season.
Fabian Hurzeler's side also showed their fighting spirit in the previous round of the Carabao Cup, recovering from two goals down to beat Manchester United 3-2 at Old Trafford.
Maresca expects another difficult challenge against opponents who are comfortable playing an aggressive, attacking game.
"First of all, they are doing very well so both games will be tough," he said.
"They are very brave, aggressive and when they have the ball they attack with so many players. They create so many chances."
City will need to be disciplined at both ends of the pitch if they are to progress to the quarter-finals.
"We need to do the right things offensively and defensively," Maresca added.
Xabi Alonso has backed goalkeeper Mike Penders to recover from his costly mistake against Tottenham Hotspur, confirming the young Belgian will start Chelsea's Carabao Cup clash with Liverpool at Anfield on Wednesday.
Virgil van Dijk has challenged Liverpool's attacking players to deliver more following Mohamed Salah's departure, although the Reds have shown encouraging signs of adapting to life without the Egyptian forward.
Mikel Arteta has warned Arsenal that their standards must be at their highest when they face Fleetwood Town in the Carabao Cup fourth round, insisting that reputation alone will not guarantee progress.
Unai Emery admits he would relish the chance to recruit some of football's finest talents but insists he is enjoying the task of building Aston Villa into a team capable of challenging at the highest level.
