Borussia Dortmund sporting director Michael Zorc has revealed that they do not know when attacking midfielder Ilkay Gundogan can play again.
Gundogan has been out of action since August because of a back problem and has made just three competitive appearances this season.
The 22-year-old is said to have suffered a further setback in his recovery, with reports indicating that he is set to spend further time on the sidelines with an inflamed nerve in his back.
And Zorc admitted that Dortmund are in the dark as to when Gundogan will make his return.
"He's just not making much progress," Zorc told Bild.
"We do not know when he can play again."
The news of Gundogan's struggles come after Marco Reus (ankle) and Sven Bender (groin) both pulled out of the Germany squad for their upcoming FIFA World Cup qualifiers with Republic of Ireland and Sweden.
They are joined on the injury list by team-mates Jonas Hofmann and Nuri Sahin, with the latter ruled out for up to three weeks with an ankle problem.
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