Cole Palmer's fitness leaves Chelsea uncertain ahead of Arsenal clash
Palmer has started this season with seven goals and five assists in 10 Premier League games, helping to lift Chelsea up to fourth in the standings.
Palmer was not registered in Chelsea's Conference League squad for the group stages, which meant he did not play in Thursday's 8-0 win over Noah, but he has not trained this week.
"Cole is getting better, but because he can walk and have dinner doesn't mean he is completely fit," Maresca said.
"He is getting better and we still have two days to prepare for the game. Hopefully, we can have him for a session - at least on Saturday - and then we take a decision."
Arsenal are level with Chelsea on 18 points as the north London side look to get out of a slump and gain a foothold in the title race with Liverpool and Manchester City surging ahead.
"I like to get pressure from these kinds of games. The pressure is also for us. For sure, they are the closest one with City. Both I consider better than the rest," Maresca said.
"The reason why is because one club is working with the same manager for nine years and the other one is working with the same manager for five years. This is a big advantage compared to the rest.
"But we're going to try to make life difficult for them on Sunday."
Arsenal beat Chelsea 5-0 in their last meeting before Maresca took charge and the Italian said he is wary of their set-piece threat.
"Mentally it will be very tough. Set pieces, they are very good. I watched the Champions League game against Inter Milan and every corner was smelling of a goal," Maresca said.