Ballack said: “He was only 21 or 20 then. He learned from other strikers and we had good strikers at Leverkusen.
“He came in all the time and you could see in training every day that he was a fantastic footballer, left and right footed.
“He was very relaxed on the ball, he keeps his cool in every situation on the pitch and that is a great point for him.
“I thought he would be a success in England, why not? He is a good player and if you score you are in the spotlight.
“He has a great future. He looks happy on the pitch and you can see that from the way somebody plays.
“He is happy with his movement and the fans – and he can score.
“I think it was a good move for him to come to England. At the moment I think he is very dangerous.”