Palmer missed last night's 5-1 win at West Ham after breaking down in the pre-match warm-up.
Maresca said afterwards: "Cole in the last four or five days was not 100%. Today he tried the warm-up, but he felt something. So we prefer not to take any risk to get worse. And we'll see in the next hours if it's something important or not.
"And then, for sure, Joao Pedro, Liam, Estevao, Jamie Gittens will be good for sure. They are all fantastic players. You can see that probably Liam and Joao are a little bit more ahead of the rest. But the reason why is because they were already here in England.
"Jamie needs to adapt a little bit, Estevao needs to adapt, Hato needs time to adapt. But overall, we are very happy with the road there."
On Palmer, he added: "The Palace game, he was not 100%. But he is trying to make a big effort for the club, for the team, for the fans. Tonight again he tried again, but it was not very good."