Bayern Munich may be forced to turn to academy coach Tom Starke in goal again after backup keeper Sven Ulreich sustained a finger injury in training.
Ulreich, 29, is currently serving as Bayern's first-choice keeper, with Germany international Manuel Neuer making slow progress toward his comeback following three foot injuries last year.
Ulreich was forced out of Bayern's second training session in Doha, Qatar, on Wednesday and will now undergo further tests to determine the extent of the issue.
A post on Bayern's Twitter account read: "Sven Ulreich has left training early, and gone for a scan on his right middle finger."
Bayern, who return to action against Bayer Leverkusen on Jan. 12, had to field Starke last month after the 36-year-old came out of retirement in September.
Bayern sporting director Hasan Salihamidzic said: "Ulle [Ulreich] is in hospital for further examinations. I'd like to think that he will be back in goal for our match versus Leverkusen."
Ulreich has proved highly effective this season in Neuer's absence and on Tuesday he was named the best German keeper in the Bundesliga in kicker's prestigious ranking of German football.
Former Real Madrid and Germany keeper Bodo Illgner said Ulreich could come into contention for Joachim Low's World Cup squad.
Illgner wrote in a column for kicker: "If Neuer should indeed miss out on the World Cup, which is something nobody wishes upon him, you should be allowed to ask the question: 'Why shouldn't Ulreich become the third keeper?'"