Benjamin Pavard has suffered a metatarsal ligament injury and is out "for the foreseeable future," Bayern Munich have announced.
The defender was forced out of a team training session on Sunday and will now almost certainly miss the club's Champions League last-16 game against Chelsea on August 8.
Bayern hold a 3-0 lead going into the second leg of that tie but Pavard's likely absence is a blow for Hansi Flick's men, who harbour hopes of winning the competition after finishing their Bundesliga campaign in fine form.
Reports in Germany indicate Pavard sustained the foot issue when he attempted to block a cross during a practice game.
"Bayern will have to manage without Benjamin Pavard for the foreseeable future," read a club statement.
"The German record champions' right-back was forced to abandon team training on Sunday morning with an injury.
"A thorough examination by the Bayern medical unit revealed a ligament injury to the left tarsal."
Pavard's absence means Flick will have to change the back four that helped secure victory over Bayer Leverkusen in the DFB-Pokal final earlier this month.
The head coach will have the chance to his assess his options - including the fit-again Niklas Sule - in Friday's friendly against Marseille at the FC Bayern Campus.