Joris Mathijsen, Hamburg's Dutch defender, faces a period out after he picked up an ankle injury during an international friendly against Turkey in midweek.
Mathijsen returned to Hamburg with his leg in plaster and will have to wait some days for further tests to determine the length of his absence.
"At the moment his leg is still too swollen to do anything," club spokesman Joern Wolf said.
Hamburg play away at Hannover today.
Michael Ballack, the Germany and Bayer Leverkusen captain who is out with a shin injury, is on track to return after the winter break. The 34-year-old midfielder also is hoping to help his team challenge for the Bundesliga title. "The crutches are gone and that is a big step. If we are all healthy then we can launch an attack for the top spot," the former Chelsea midfielder told the Bundesliga website.