Manchester United and Arsenal target Ilkay Gundogan has been hit with the news that he may be out of action until the end of the year, according to Goal.
The 22-year-old, who was an integral part of the side that Jurgen Klopp steered towards the Champions League final last season, has been sidelined since August with a back injury, and Dortmund's sporting director, Michael Zorc, has affirmed that the situation has not got any better.
"He is not making any progress at the moment," Zorc is quoted as having said.
"We do not know when he will be able to play again."
The German international aggravated a back problem whilst on duty with the national team in August and has since only made one appearance for Dortmund this campaign.
The club's medical team are thought to have established that the cause of the problem is an inflamed nerve, which would potentially force Gundogan out until at least January.
The news may impact the transfer options of United and Arsenal, who are both keen to sound out Dortmund about the midfielder's availability in January.
The injury will almost certainly complicate matters and there's no guaranteeing that Gundogan would be fit to pass a medical in the New Year if a move were to be agreed upon.