He said: "Kaka is a phenomenon, but he got injured in the last World Cup and had to have an operation on his knee.
"Then [Mesut] Ozil arrived and took his place in the team from him, but he is still one of the greats of the game. He is the second most followed footballer on Twitter, after Cristiano Ronaldo.
"He is charming and excites the fans. I'm optimistic that, under Ancelotti, who knows him very well, he can be the same magical Kaka again that we signed."