Serdar Tasci sustained a head injury in his first Bayern Munich training session and appears to have suffered minor concussion, sporting executive Matthias Sammer has said.
Bayern signed Tasci on loan from Spartak Moscow on deadline day to cover for what club president Karl Hopfner has described as a "bad patch" with injuries, with the centre-back set to provide cover during the absences of Jerome Boateng, Javi Martinez and Medhi Benatia.
The club invited reporters to greet the new signing in Munich on Wednesday, but the former Germany international was unable to attend after an incident at his first session with his new teammates.
"He had a collision and in the aftermath showed symptoms," Sammer said. "It indicates he suffers from a minor concussion."
Bayern's sporting executive added that he expects Tasci to be sidelined for two or three days, and that further examinations will show whether he can make the squad against Bayer Leverkusen on Saturday.
Holger Badstuber, whose career has been blighted by injury over recent years, is currently the only recognised senior centre-back available to coach Pep Guardiola, with the likes of David Alaba, Xabi Alonso and Joshua Kimmich having been forced to act as central defenders.
Meanwhile, Bayern and Arturo Vidal are set to take legal action over a report claiming the midfielder left the club's training camp in Qatar several times and upon his return smelled of alcohol.