Borussia Dortmund defender and captain Mats Hummels is in talks with rival club Bayern Munich for a possible transfer there after his contract expires in 2017, according to German newspaper Bild.  
Hummels, a product of Bayern Munich’s youth academy, debuted in the Bundesliga under Ottmar Hitzfeld, but left for Dortmund in 2008. 
Dortmund would have to sell him this summer if he does not extend his contract, or risk losing him on a free transfer.
On Wednesday, Hummels told SkySports: 'I've set myself a date by which I have to decide [about his future]. It's a very difficult decision for me. I'm losing about half an hour's sleep every night just thinking about it. When I finally make my decision, people will see why it has been so difficult.”
In 2013, Bayern controversially prized away midfielder Mario Gotze, a key part of Dortmund's run to the Champions League final. He was left out of the team for that final after news emerged that he had already agreed a contract with Bayern.
The next year, Bayern also signed up Dortmund's prolific striker Robert Lewandowski.