Hamburg CEO Carl-Edgar Jarchow has admitted that the club are frustrated by Son Heung-Min's reluctance to discuss his future until the end of the season.
The 20-year-old, whose current deal with the German club runs out next summer, has said that he will decide his next move only at the end of this campaign.
"It's a truism: If a player only has one year left on his contract the club tries to prolong with him – or they agree to part ways," Jarchow told Die Welt on Tuesday.
"No club wants a player to leave on a free, no club can allow itself to give away millions. He wants to wait for the end of the season and God knows why."
Hamburg general manager Frank Arnesen said earlier this week that Son could be sold this summer if he decides not to extend his current contract.
Germany
Switzerland
Hungary
Scotland
Spain
Italy
Croatia
Albania
England
Denmark
Slovenia
Serbia
Austria
France
Netherlands
Poland
Romania
Belgium
Slovakia
Ukraine
Portugal
Turkey
Georgia
Czech Republic