Bayern Munich face an anxious wait to discover the severity of Joshua Kimmich's knee injury which cast a shadow over their 3-2 win at Borussia Dortmund on Saturday which sent them top of the Bundesliga.
The Germany midfielder, who has been in great form recently, was helped off in obvious distress after twisting his knee in a first-half challenge.
"He'll fly home with us and be examined - it's too early to say the extent of the injury," said grim-faced Bayern coach Hansi Flick.
Kimmich is also a concern for Germany ahead of the friendly against the Czech Republic on Wednesday before Nations League games against Spain and then Ukraine in the following six days.
Bayern earned their fourth straight win over Dortmund as Robert Lewandowski scored his 11th goal in just six league games.
After Marco Reus gave Dortmund the lead, David Alaba blasted home a free-kick to make it 1-1 at the break before Lewandowski struck with a superb header early in the second half.
Lewandowski, the European player of the year, could have finished with a hat-trick after the VAR ruled out further efforts either side of half-time.
Leroy Sane came off the bench to grab Bayern's third ten minutes before the final whistle while Erling Braut Haaland scored Dortmund's late second goal.
However, Flick admitted the potential loss of midfield dynamo Kimmich would be a blow for the European champions.
"He's a very important player for us and with his mentality, he isn't someone you can replace like for like," said Flick.
The Bayern boss was pleased with the win which left his side two points clear of second-placed RB Leipzig. Dortmund are now third, three points behind Munich.
"There were many, many chances to score on both sides," enthused Flick.
"In the end we were a little more determined, that's why I think the victory was more than deserved.
"Dortmund were dangerous when we made mistakes, which we must put a stop to."
Dortmund head coach Lucien Favre said it was "hard to accept" conceding three goals at home to Bayern.
"All in all, we have to be positive, we did a good job - we had so many chances to score," lamented the Swiss.
Haaland was annoyed at his own performance after converting one of his four chances.
"I have to score more goals, if we don't put our chances away at this level, then we won't win," said the 20-year-old.
"They are the best team in the world, but we have to work harder to take the next step to be as good as them."