Hummels' father: Dortmund skipper could return to Bayern

It has been taking Borussia Dortmund skipper Mats Hummels "at least half an hour extra to fall asleep for several weeks" due to the constant speculation surrounding his future, and his father admits it could lie with Bayern Munich.

A host of clubs including Bayern, Barcelona, Liverpool, and Manchester United have been linked with a move for Die Borussen's skipper this summer, and that transfer tattle has had the 27-year-old reaching for the snooze button.

"It's a very difficult decision, and when I finally make it people will understand how hard it is for me," Hummels, who has been at the Westfalenstadion on a permanent basis since 2009, told Germany's Sky television via the Guardian.

"It's been taking me at least half an hour extra to fall asleep for several weeks now because this is such a big issue for me."

The defenders father and agent Hermann Hummels shares his quandary, and does not rule out a return to Bayern where his son was a peripheral member between 2005 and 2008 before moving to Dortmund.

"Mats is facing an enormously important decision in his career, in his life," said Hummels Sr. "Dortmund are back among Europe's best clubs and that is making the decision even harder for him. If he were to leave Dortmund, then he could only go to five or six top clubs, and of course Bayern are one of them."

Mats Hummels will be expected to start when Dortmund visits VfB Stuttgart on Saturday.