According to reports, Chelsea have zeroed in on making Bayer Leverkusen midfielder Havertz their next acquisition after signing Timo Werner and Hakim Ziyech, and the Blues are hoping to complete a £70m deal after the German club finish their Europa League campaign this month.
A move is not necessarily certain to happen, but Manchester City midfielder and international team-mate to Havertz, Gundogan, believes that should Chelsea get their man, he will eclipse the efforts of Ballack, who spent four years at Stamford Bridge between 2006-10.
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"In my opinion, Havertz is even better than Ballack in terms of his playing ability," Gundogan told SportBild. 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."
Gundogan has admitted to being wary of Chelsea's threat next season, insisting he is full aware of the qualities new Blues signing Werner will bring to the Premier League.
"Believe me: Everyone at City knows about Timo Werner. Many of my team-mates asked what kind of guy he is. He deserves respect," Gundogan added.