Ahead of facing Brighton today, Nuno said: "It was a nice surprise. I didn't know him very well. But since we have started working together I've been impressed by his quality.
"There are a lot of details he can still improve on but he has performed really well and I think he has all the characteristics to become even better.
"He is fast, he is good on the ball, he is a good defender. He is doing really well.
"When we arrived he was already here and he was playing. So then it was about continuing the work Steve (Cooper) was already doing with him and trying to raise his standards. We set him a very high level because I believe he can reach that."
On Murillo winning a first Brazil cap, Nuno added: "Come on, the best thing we can do for Murillo is for everybody to keep our feet on the ground. We have to realise he is 21 years old and he has come to a different country and a different competition.
He is doing really well but there is still a long way to go and a lot of things to improve, but the fact he is committed to improving is important. He's a nice boy, a very professional player and a really nice guy."