Bastian Schweinsteiger suffered a blow on his road to recovery after it was revealed on Friday the Bayern Munich stalwart will undergo further ankle surgery after problems arose following the first operation in June.
It is unclear how long the 29-year-old will be sidelined but the club said the midfielder would be operated on soon.
Initial attempts to treat the problem without surgery failed.
The Germany international will miss friendlies against England and Italy this month.
Schweinsteiger was ruled out for much of pre-season training after needing surgery following their treble-winning campaign last season.