Bayer Leverkusen head coach Peter Bosz lauded "special player" Kai Havertz but insisted the in-demand star can improve amid growing interest.
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.
After thrashing relegation-threatened Bremen behind closed doors at Weser-Stadion due to the coronavirus pandemic, Bosz told reporters: "Kai [Havertz] is a special player, but I don't think he made his best game today. He can do much better.
"I've known him for a long time now and I know he can do much better. It has to do with the rhythm. But for every player the captain's armband is something special. And so it will be for Kai."
Havertz, 20, added: "I'm very happy. We didn't make many mistakes and deservedly won.
"Now we want to continue like this on Saturday in Monchengladbach."
The result was Leverkusen's fourth in succession as the Bundesliga returned over the weekend following the COVID-19 outbreak.
Leverkusen are fifth in the table, eight points behind defending champions and leaders Bayern Munich.
"We are naturally satisfied, as you have to be when you win the first game after a two-month break with 4-1 in Bremen," Bosz said. "There were many question marks before. I think we deserved to win, although we didn't always play very well. That has to do with the rhythm.
"We lost easy balls during the game, which we normally don't lose. But like I said, if you win 4-1 here, you have to be satisfied. And I am satisfied."