Celtic have been warned they'll need to keep the new Kai Havertz quiet when they return to Europa League action on Thursday.
The Parkhead club welcome Bayer Leverkusen for their second group game, having been on the wrong end of a thriller at Real Betis in the opening round.
Manager Ange Postecoglou is uncompromising in his devotion to open and attacking football, and will be sure to go for it against the Bundesliga outfit.
At the other end though Celtic will have to worry about 18-year-old rising star Florian Wirtz, already a German international and linked to Real Madrid.
And sporting director Rudi Voller reckons the attacking midfielder is even better at his age than £75million man and Champions League winner Havertz.
Voller said: "The speed in which Florian is developing is very special indeed.
"Just like Kai Havertz, he has everything you need to be a world class player. He's probably ahead of where Kai was at his age.
"There's no question he is going to be a fantastic player.
"He is not only developing rapidly as a player, he's growing as a leader on the pitch too. For example, he's the first to help out his teammates if it gets heated on the pitch.
"For us at Leverkusen, we are going to be very proud when Kai and Florian play together for years in the Germany midfield in the future."
