Borussia Dortmund defender Mats Hummels is considering the prospect of a return to Bayern Munich, according to club chairman Karl-Heinz Rummenigge.
The 27-year-old has been heavily linked with a move away from Signal Iduna Park at the end of the season, with his contract due to expire in 2017.
Speculation has grown that Hummels, who has said he is losing sleep while agonising over his future, would prefer a move back to Bayern, where he progressed through the youth ranks.
Rummenigge would not be drawn on any possible talks with Dortmund, but claims the player is open to a transfer.
"I can echo [Dortmund chief executive officer] Hans-Joachim Watzke's words - Mats Hummels is thinking about FC Bayern," he told the media prior to Bayern's trip to face Atletico Madrid. "But in every transfer three parties are involved.
"I don't want to go into depth today, we will have to stay calm and wait. There is still lots of time until the end of that transfer window."
Watzke admitted on Monday that Dortmund would not stand in Hummels' way if he makes it clear he wants to leave.