Bayer Leverkusen head coach Peter Bosz lauded "special player" Kai Havertz but insisted the in-demand star can improve amid growing interest from some of the world's top clubs.
Havertz continued to burnish his reputation with a first-half brace as Leverkusen crushed lowly Werder Bremen 4-1 in the Bundesliga on Monday.
The Germany international – frequently the topic of transfer gossip columns amid links to Liverpool, Manchester United and Arsenal – opened the scoring in the 28th minute and restored Leverkusen's lead five minutes later following Theodor Gebre Selassie's equaliser.