Robert Lewandowski continued what has felt like a one-man argument for the Bundesliga's status quo as he inspired Bayern Munich to a 4-0 Klassiker victory over Borussia Dortmund at the Allianz Arena.

On the face of it, these are changing times in Germany's top flight, not least for Bayern.

The reigning champions were playing their first league game under interim head coach Hansi Flick after Niko Kovac didn't so much run out of road as go careering off the autobahn during last weekend's miserable visit to his old employers Eintracht Frankfurt.

Lewandowski got Bayern's goal to briefly punctuate the misery at the Commerzbank-Arena. Of course he did.

Saturday's opener to begin another Dortmund ordeal in Bavaria continued his run of scoring in every Bundesliga and Champions League game this season.

The Poland star's coolly taken second 14 minutes from time moved him on to 23 in all competitions for Bayern in 2019-20 before the November international break.

Lewandowski is an elite performer operating at the irresistible peak of his powers and a bedraggled BVB had no answer.

Julian Weigl criminally switched off as he ghosted in to head home in the 17th minute, although Dortmund had no more joy against the mighty number nine when their collective gaze was fixed upon him.

Kingsley Coman was unable to turn in after Lewandowski spun intelligently into the channel and he was also involved in both Serge Gnabry's offside effort before half-time and legal goal afterwards.

Back at Dortmund after his Bayern sojourn, it felt like Mats Hummels was fighting a futile battle against his own team-mate. The indignity of putting through his own net to complete the rout would have been a better fit for most of the other insipid performers in yellow and black.

Borussia Monchengladbach can go four points clear at the summit if they beat Werder Bremen on Sunday, while RB Leipzig remain ahead of Bayern on goal difference thanks to a thrilling 4-2 win at Hertha Berlin.

Marco Rose and Julian Nagelsmann are two exciting young coaches threatening to shake up the established order and it seems clear that is where the challenge to Bayern's supremacy now resides.

It is a task beyond Dortmund, who wear the scars inflicted under the yoke of their bitter rivals too visibly, while picking up fresh ones on each trip to Munich.

Jadon Sancho, the future superstar earmarked to end the suffering, was ignominiously substituted in the 36th minute of a loss that continued a hideous Bundesliga run at Bayern.

4-0, 5-0, 6-0, 4-1 and 5-1 are their past five league scorelines at the Allianz. The pain has become unrelenting.

Their previous win on enemy territory in the league was a 3-0 victory in April 2014, the only catch being Bayern had already won the title by that stage.

Jurgen Klopp was the Dortmund head coach that day. The seasons when he lifted the club to new heights and made Der Klassiker a European fixture to rank alongside the Spanish argument from which it cribs its name feel like they belong to a completely different era.

Incumbent BVB boss Lucien Favre would probably be joining Kovac in a period of enforced leisure time if not for Tuesday's stirring comeback against Inter in the Champions League, but his brittle squad are making a mockery of those pre-season tips for Bundesliga glory.

This is how they deal with Bayern in a time of crisis. They do not have a prayer. If things are to actually change, it's over to Gladbach and Leipzig.

From the moment Lewandowski brought them under his brutal spell, Dortmund's fate felt inevitable. A once vital fixture has become a painful procession to watch through your fingers or not at all.