The Manchester United loanee was impressive for their Europa Conference League win at Heidenheim last night.
Maresca said, "It’s very important he was back.
"I have said since we started that Jadon is very important for us. He has to be fit mentally and physically, because he is going to help us a lot.
"Unfortunately we couldn’t use him for a few games, but last night he showed again how important he is for us.
"He is what we need, especially against a team that defends with a low block. We need that quality in the last third, the last pass and he can shoot, sometimes he will shoot more than he did against Heidenheim. But I think he is going to help us a lot."
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