After signing for Bayern Munich on Monday, Serdar Tasci may be ruled out of a possible a debut against Bayer Leverkusen on Saturday.
The defender clashed heads with a team-mate on during training on Wednesday, suffering a "mild concussion" according to the official Bundesliga website.
The incident - in his first session with his new side - meant that Tasci missed his official unveiling at the club.
Another injury Bayern didn't need
Tasci had been brought in as defensive cover on Deadline Day from Spartak Moscow, with the Bundesliga champions currently suffering from a defensive crisis.
Jerome Boateng picked up a serious injury against Hamburger SV that will see him miss at least half of the Rückrunde.
To make matters worse, Javi Martinez was also sidelined not long after the turn of the year. The Spaniard had seemingly left his injury problems behind.
Rounding the injury troubles off, Mehdi Benatia is still out with a knock he picked up in December. He is expected to return soon, however.
Crumb of comfort for Tasci
Despite the suspected concussion, Tasci did give his thoughts on the move to Bayern's official website.
“It was really good after such a long break,” he said. The 28-year-old has been out of action since early December with the Russian winter break, but is still not out of shape.
After completing a programme with Dr Holger Broich, Tasci explained: “I completed the Spartak winter training camp, so I’ve already worked on the fitness basics.”
Upon his arrival, the defender described it as “all really super", believing that the Säbener Strasse “has everything that marks out a truly top club".
He concluded, "I’m overjoyed and I’m really looking forward to training with the team tomorrow. I just want to go for it now.”