Sanchez's impressive goalkeeping performance secured a clean sheet for his team and frustrated Evanilson, who missed a penalty in the 1-0 victory.
Maresca later said: "I am very happy with him and it is not only this game.
"Since we have started, Robert is doing very well with us. He is doing well on the ball, in terms of when we need to build, and he is doing very well off the ball when he has to save.
"We are very happy with him."