Bild report that FC Köln midfielder Salih Özcan is currently undergoing a medical with Borussia Dortmund.
The 23-year-old has just one-year remaining on his contract at Köln and will join BVB for a reported €10m.
Özcan signed a contract extension last summer after the Turkey international had interest from Rangers. With the departure of Axel Witsel, head coach Marco Rose wanted to sign a new No. 6.
After Karim Adeyemi, Niklas Süle and Nico Schlotterbeck, Özcan will be the fourth arrival.