Schalke sporting director Horst Heldt is determined to hang on to central defender Kyriakos Papadopoulos amid interest from Zenit St Petersburg.
Russian champions Zenit are reported to have made a 15 million euro bid ($18.7 million) for the 20-year-old Greece international but Heldt said he hopes to keep one of his club's prized assets in Gelsenkirchen ahead of Friday's transfer deadline.
"They have made an offer and are being very persistent but we do not want to lose the player," he told www.kicker.de.
Heldt was speaking after Schalke opened their Bundesliga campaign with a 2-2 draw at Hannover on Sunday.
Having overturned a 1-0 deficit to lead 2-1 with 10 minutes to go, the visitors were frustrated not to have taken all three points.
Midfielder Lewis Holtby, who grabbed Schalke's second goal after Klaas Jan Huntelaar had canceled out Felipe's opener, said: "I am disappointed.
"We were clearly the better team and controlled the game, making plenty of opportunities. But we conceded two stupid goals."