The youngster was handed a full Premier League debut on the day.
Maresca explained: "All the players, for me, were good today but if I had to decide for one, I think for sure, Josh was our best player because of his age, it was his first game. Josh, for me, can be a top player for this club but he needs the right path, the right moment; for young players, you need to decide which moment.
"We decided today because we think he showed that he was ready. Today, I think he showed how good he is. Because of his age, he needs to slow down, work hard and take his next chance.
"Even if we don't decide to buy players or sell players because Josh has shown he is good. We already knew Josh was good enough. Probably with Wes (Fofana) and Benoit (Badiashile) injuries, we will see if something is going to happen."