The report claims that Manchester United are preparing a move and that the Red Devils sent scouts to watch the 21-year-old playmaker in the 4-4 draw against Roma in the Champions League last week.
Bayer CEO Michael Schade revealed that he wants Hakan to stay at the club but that they will listen to offers that match their release clause for the Turkish international.
Schade said: “We want to keen Hakan but there is a pay threshold.”
TalkSport have also closely linked Arsenal with Çalhanoğlu but the Gunners could face competition from the likes of Manchester United and Barcelona who are reported to be keeping tabs on the 21-year-old sensation.
The Turkish international has been closely monitored by Barcelona who are in the market for a new midfielder following injuries to Rafinha, Lionel Messi and Andres Iniesta last month.
The rising star has already scored six goals and provided two assists in all competitions this season and also has a phenomenal free-kick scoring record – 22 in the Bundesliga alone.