Bayern Munich have woes out wide for Wednesday’s Champions League match at Anderlecht, with left backs David Alaba and Rafinha both injured.
Alaba twisted his back and Rafinha took a knock to his ankle, which have sidelined them both for the game against the Belgian side.
The pair are also doubtful for Saturday’s away match when Bundesliga leaders Bayern are at Borussia Moenchengladbach.
Bayern head coach Jupp Heynckes will have to rearrange his defence after resting Alaba and playing Rafinha at left back in Saturday’s 3-0 league win at home to Augsburg.
Bayern are already missing goalkeeper Manuel Neuer and winger Franck Ribery, while Germany forward Thomas Mueller has only just recovered from a leg injury.
The Germans have already qualified for the last-16 in Europe, while Anderlecht have lost all four games so far.
The Bavarians are on a roll, winning all eight games since Jupp Heynckes replaced Carlo Ancelotti at the end of September.
“We are on a run, and you have to stay in this flow,” said Bayern chairman Karl-Heinz Rummenigge.
“I do not think the positive tension in the team will drop – Jupp will not allow that.”
Bayern need to beat Anderlecht to stay in touch with Paris Saint-Germain, who are three points ahead in Group B.
The French league giants have won all four games in Europe before Wednesday’s home match against Celtic, and face Bayern in Munich on December 5.
Having lost 3-0 to PSG in Paris last September, Bayern have only a slim chance of winning the group.
They are likely to go into the final group match needing to beat the French 4-0 in Munich unless PSG slip up against Celtic.
“Paris has cleaned up everything in the Champions League, and while I make no secret of the fact that we want to win at least on 5 December, I’m not optimistic about a 4-0 win,” Rummenigge added.