By ESPNSTAR.com staff
Sahin started his professional career at the Signal Iduna Park and was a key member of the side that won the Bundesliga title in the 2010/11 season.
His fine performances saw him earn a €10million move to Real last summer but injuries have so far hampered his attempts to earn a spot in Jose Mourinho's starting XI.
In total, Sahin made just ten appearances for Los Blancos last season and has repeatedly been linked with a move away from the Santiago Bernabeu, with Dortmund named as a likely destination.
However, Watzke has denied claims BVB are currently planning to re-sign the Turkey international, although he revealed the player is always welcome at the club.
"Sahin coming back to us is not planned, either by him or us," he told Sport Bild.
"However, he's a boy with a Dortmund past and he came from our youth team, so I would never rule out a return."
Should Sahin remain at the Bernabeu for the coming season, he will have to battle with the likes of Xabi Alonso, Sami Khedira, Mesut Ozil and Kaka for a place in the Real line-up.