Borussia Dortmund insist Neven Subotic is not for sale after Manchester City were linked with a £20million bid for the defender.
Speculation on Sunday claimed that City boss Mark Hughes had lined up the 20-year-old as the next big-money arrival at the club in January.
Hughes brought in Kolo Toure and Joleon Lescott during the summer, but reports claim he wants further additions to his back-line.
Subotic is highly rated in Germany and the former Mainz youngster has previously been linked with City's Premier League rivals Arsenal, Chelsea and Everton.
However, Dortmund general manager Hans-Joachim Watzke is adamant Subotic will not be leaving the club in New Year even if City make a £20m offer.
"They could easily make us this offer if they would like to," said Watzke.
"But we are staying firm to our vow - Neven Subotic is not for sale."
Subotic, who signed a new five-year contract in the summer, is flattered by City's reported interest, but is in no rush to leave the Bundesliga club.
He told BILD: "It is a big honour if such a big club is attempting to sign me, but I am under contract until June 2014 at Borussia Dortmund and still want to achieve many things with this club."