The pair also played together for the Spain U21s.
He told the Telegraph: "David can become the best goalkeeper in the world. Maybe at this moment David is. Manuel Neuer doesn't receive so many shots because Bayern (Munich) is much, much better than the other teams in Germany.
"Here in England, they test David and he makes fantastic saves. He's also very good with the ball. When one centre-back passes the ball to him, he can change the play to the other side. Unbelievable."