The 20-year-old Belgium international joined the Blues in January from Racing Genk, with the plan that he would be loaned out this summer.
Now Werder have emerged as favourites to clinch his signature, and although a deal is yet to be confirmed - they are edging closer.
"We have an interest in the services of Kevin de Bruyne and, of course, we are in talks," Tino Polster, media spokesperson of Werder, told Kicker Sportmagazin.
"Those talks are progessing very well. And we are hopeful to conclude the details soon enough. But by now the deal is not a done deal."