The Spaniard, 24, was full of praise for Toure, whom he described as one of the best midfielders in the world. Mata and Toure are likely to come face-to-face at Wembley, but Mata warned that he and his Chelsea colleagues will have to stop the rest of the City side as well as former Barcelona star Toure.
"Yaya is one of the best midfielders in the world," Mata told The Sun. "He is the complete player. He can defend, attack, score, dribble, he has great skills and he's so tall and powerful."
He added, "It is so difficult to defend against him. We have very good midfielders too and will try to deal with him but not just him, all their team because City are a very, very good side."
Sunday's visit to Wembley will be Mata's fourth as a Chelsea player and fifth overall as the midfielder appeared in Spain's 1-0 loss to England in 2011, and he admitted the stadium holds a particular place in his affections.
"In my first season in England I won my first trophy with Chelsea there — the FA Cup — so it is a very special venue for me. But even when I was playing in Spain I realised that Wembley was one of the most important football stadiums in the world because of all its history staging the big matches and so many finals.
"Then, after I came to England, I experienced what it was like to actually play there. My first match there was for Spain against England last season and then with Chelsea I really enjoyed the semi-finals and final of last year's FA Cup."