Stuttgart chairman Gerd Mauser is unwilling to negotiate the sale of Bernd Leno to Bundesliga rivals Bayer Leverkusen.
The 19-year-old goalkeeper has admitted he would be interested in staying at BayArena ahead of the December conclusion of his loan.
But Mauser insists the Germany youth international will return to Stuttgart and he is considered one of the stars of the future.
Mauser told Die Welt daily: "Bernd Leno is a crown jewel for us. We do not want to sell him.
"To just make us think about this, we would need to receive an offer that makes us feel dizzy."
Meanwhile, Germany international and Stuttgart captain Cacau has slammed reports he is involved in a massive dispute with team-mate Martin Harnik.
Cacau told kicker-Sportmagazin: "Some media have created this fuss out of nothing."