The defender has made an instant impact since joining from Crystal Palace in the summer.
Mata told The Times: “He's very, very good in defensive duties, very good in tackling.
“I've never seen any player like him, he's unbelievable.
“Even in training you think you're past him and then he comes and takes the ball straight. He has very long legs! I can only see him improving.
“Like Anthony, he's a shy, reserved guy but confident on the pitch."