Bayern Munich's Joshua Kimmich has been ruled out until January after having surgery on a knee injury he suffered during the 3-2 Klassiker victory over Borussia Dortmund.
The German international had an operation on his right lateral meniscus on Sunday evening.
Kimmich was forced off injured in the 36th minute of the 3-2 win in the Bundesliga top-of-the-table clash.
Bayern have said that their medical staff expect Kimmich to be available for selection again in two months.
Hasan Salihamidzic, a Bayern board member, said: "We're glad that Joshua (Kimmich) will probably be available again in a matter of weeks.
"We'll support him in his rehabilitation as best we can."
Bayern hold on to win Klassiker thriller
Robert Lewandowski kept up his sensational Klassiker form as Bayern Munich topped the Bundesliga with a rollercoaster 3-2 victory at Borussia Dortmund.
Lewandowski - who also saw two other goals ruled out by VAR - netted his 22nd goal against his former employers from Lucas Hernandez's cross three minutes after half-time to give the visitors the lead for the first time in the game, with Marco Reus' close-range finish moments before the break already cancelled out by David Alaba's deflected effort in first-half injury time.
Bayern proved the more clinical side in an end-to-end game as substitute Leroy Sane added a third following a fine run from midfield (80), before the otherwise wasteful Erling Haaland gave Dortmund hope from Raphael Guerreiro's ball in behind (82).
But in a match the hosts may have felt they deserved more from, it was their visitors who went top of the Bundesliga, ensuring Hansi Flick kept up his 100-per-cent record against Bayern's biggest rivals and secured their sixth win from seven league games.