Manchester City midfielder Ilkay Gundogan says Kai Havertz will prove a big hit at Chelsea.
Bayer Leverkusen ace Havertz is a key target for Chelsea, who have already signed Timo Werner this summer.
Gundogan plays with Havertz and Werner for Germany and is aware of how good the pair can be at full flow.
He said: "In my opinion, Havertz is even better than (Michael) Ballack in terms of his playing ability. Ballack had a certain level of aggression in his game, and a strong mentality.
"He was a top player of the previous generation - a b*****d on the pitch, in a positive sense. Kai isn't like that."
