The 22-year-old, who spent a loan stint at the German club last season, has started in just two league matches this season and was left out of the Champions League squad that went on to beat Steaua Bucuresti 4-0.
"Should Kevin be unhappy, we are an eager first contact," Sky Sports News quotes Eichin as saying. "I'm in contact with his agent and I'm informed about Kevin's situation at Chelsea.
"I know Kevin, if he doesn't play, it is certainly a big problem for him. Let's wait and see what happens in the winter. We will be ready if there's a possibility to get him."
The Belgian signed for Chelsea from Genk last year.