Materazzi says new coach Leonardo has put the smile back on the players.
"Leonardo is an intelligent person who has brought back the smile and the desire to play football," said Materazzi. "I speak of those who have returned with a smile, the same who previously had been left out.
"In life, you also make mistakes: we are a Formula One car, but there must be a pilot. If you put a policeman there, things do not work ..."
Matrix added "AC Milan? They're strong winter champions, but we are world champions and we want to believe it."