The transfer rumour claims that Çalhanoğlu would favour a move to the Premier League giants instead of Spain.
The Bild report that United are keeping close tabs on Çalhanoğlu and sent scouts to his recent Champions League clash against Roma.
Bayer have made it clear that they want to keep hold of the Turkish international who still has another four-years left on his contract but that they would be willing to listen to an offer of £28.9 million.
The highly rated 21-year-old has already scored six goals and provided four assists in all competitions this season. The Bayer play-maker star also has a phenomenal free-kick scoring record – 22 in the Bundesliga alone.
The Turkish international is expected to start for Bayer against Roma next at the Stadio Olimpico.