The crucial third Bayern Munich goal from Leon Goretzka was debated by Marco Reus and Thomas Muller after a thrilling Klassiker.
Marco Reus believes Borussia Dortmund were denied "a very clear foul" that would have been given had it been for Bayern Munich just before their rivals scored the pivotal third goal in a thrilling Klassiker.
Dortmund surrendered a two-goal lead given to them by an early Erling Haaland double as they went down to a dramatic 4-2 away defeat to Bayern on Sunday (AEST).
It looked like they would still hold on for a point until Leon Goretzka scored a volley two minutes from time, before Robert Lewandowski struck again for Bayern to seal his hat-trick.
Dortmund captain Reus had been substituted by the time Goretzka struck, but he was adamant the crucial goal should not have stood after Emre Can claimed to have been fouled by Leroy Sane in the build-up.
"It's a very clear foul," Reus said to Sky Germany.
"I tell you quite honestly that if that had been for Bayern, it would have been whistled.
"That's just the way it is. There is nothing to add. That's the way it is."
Responding to Reus' comments, Bayern attacker Thomas Muller insisted it was not the type of incident he would have liked to see whistled for either team.
"When you lose a game, it's clear that you focus on an incident like that," said Muller. "But you'll have analysed that.
"We don't want these duels to be whistled at the halfway line, otherwise we only have stop-start games.
"So I wouldn't have whistled that as a foul against us. I really, very much like the way Marco Fritz refereed today."
Despite the controversy about the key goal, Bayern had dominated much of the contest, racking up 27 attempts to just four from Dortmund while having 66 per cent of the possession.
The win moved Bayern two points clear of RB Leipzig atop the Bundesliga and left Dortmund sitting sixth, four points adrift of the top four.