Stuttgart have announced that Georg Niedermeier is likely to be out for "several weeks" after sustaining a ligament injury.
The 27-year-old picked up the injury during the side's goalless draw with Botev Plovdiv yesterday.
A statement from the club said: "The first diagnosis is a suspected torn ligament. There will be further tests to determine the exact damage.
"If the initial diagnosis is confirmed then unfortunately the defender will be out for several weeks."
Niedermeier featured in 27 Bundesliga games for Stuttgart last season.