Javi Martinez will miss Bayern Munich's next two matches at least due to a shoulder injury, coach Jupp Heynckes has announced.
The Spain international was forced off in the 70th minute of Bayern's convincing 5-0 win over Freiburg in the Bundesliga on Saturday.
The 29-year-old will not be available for the visit of Celtic to Allianz Arena in the Champions League or the trip to Hamburg in the league next weekend.
"Javi trained very well during the international break and as well last week," Heynckes told a news conference.
"That's why he was able to show a good performance until his substitution against Freiburg.
"It's a pity he is out now. But we have a good squad with other players, which can compensate for his absence.
"We assume he'll be out for a limited time. Robert Lewandowski had a similar injury and played again after 10 days.
"I am not [in favour] of letting injured players play, because they cannot show their normal performances.
"Second, it is dangerous because they can become injured again. That's why Dr [Volker] Braun and I said Javi won't be with us in the next two games.
"Then we have to see how he feels, how he trains, if he has pain, if we can stabilise his shoulder and if that's acceptable."
Bayern lost 3-0 at Paris Saint-Germain in their previous Champions League outing, a result that cost Carlo Ancelotti his job as head coach.
And defender Jerome Boateng knows the importance of getting the team's European campaign back on track under Heynckes.
"There is always pressure at Bayern Munich, but for sure it's an important game," the Germany international said.
"After a loss in the Champions League we want to answer with a win. We are very motivated to reach a good result."
Heynckes, who orchestrated the team's most recent Champions League success in 2012-13, added: "It's another competition. FC Bayern has big ambitions in this competition, the squad and me as well.
"So it would be good if we were able to live up to Saturday's game and if we were able to continue improving."