Borussia Dortmund were spared by a marginal VAR call, but it was as if something unhelpful within their collective muscle memory started to spasm.

Robert Lewandowski thought he had added to his merciless record of 18 goals in 21 competitive encounters against his former club, adding the finishing touch to a move of frictionless beauty featuring all members of Bayern Munich's dynamic front three.

Unfortunately for the superstar striker, his knee strayed fractionally offside when converting Serge Gnabry's cross and Saturday's compelling, undulating Klassiker remained goalless. Although that state of affairs was very much on notice.

Dortmund were aiming to equal a Bundesliga record of five consecutive clean sheets and had the best defensive record in the division so far this season, having conceded just twice.

Lucien Favre has made building more solid foundations for his side's flair an obvious priority. Before the weekend, they had also faced fewer shots than any other team (37) and only committed one error leading to a goal in the 2020-21 campaign.

Despite all that, Lewandowski's reminder of his lethal qualities seemed to induce panic. They were all at sea a few moments later when Leon Goretzka got a volley off and the ball spun eventually to safety from Roman Burki's save.

It felt like a case of kill or be killed and, on the stroke of half-time, BVB thrillingly struck. Mats Hummels' drilled pass was superb - putting Bayern straight back on their heels and allowing a sprightly move to fizz through Jadon Sancho, Raphael Guerreiro and finally Marco Reus, who opened his body for an expert side-footed finish.

They were unable to even make it to the interval. Hummels, the rock upon which Dortmund's new solidity is built, tore out of position and missed a challenge on Gnabry. A panicked Thomas Delaney tripped the Germany winger inside the D and a scampering Hummels was unable to clear David Alaba's deflected free-kick on the goal-line.

The early stages of the second half proved decisive and underscored the terms upon which this uneven battle is waged. Promise can challenge perfection and potential might nudge prowess out of its stride, but it's never less than a very tough ask.

Erling Haaland could very well be to the coming decade what Lewandowski was to the one just gone. The 20-year-old sensation is a striker blessed with natural gifts and a confidence that borders on arrogance.

Another fine Hummels ball found Sancho and his reverse pass released Haaland. A VAR check for offside would have been in order had he found the target, but the Norway international dragged wide.

It was, at best, half a chance. The same could be said when Lewandowski stole a few inches in front of Hummels and headed home immaculately from Lucas Hernandez's left-wing delivery in the 48th minute.

Bayern sensed blood and Champions League final hero Kingsley Coman thudded a drive against the post. To their immense credit, Dortmund turned the tide and sent wave after wave crashing towards Manuel Neuer's goal.

Haaland tormented Jerome Boateng relentlessly, but his radar was off. Teenager Giovanni Reyna shot at Neuer following a mistake from Bouna Sarr, who endured an at times tortured introduction to this fixture.

Jude Bellingham, 17, came on to turn the midfield in Dortmund's favour and fellow substitute Thorgan Hazard drew a superb Neuer stop, as did Reus.

Then, in the 80th minute, when Haaland's hold-up play misfired, Bayern broke and Leroy Sane - a ready-made world-beater from their bench - scored a riotous counter-attacking goal.

It ended 3-2 as Haaland finally got the goal his endeavours deserved, bringing down Guerreiro's chipped pass brilliantly and rounding the goalkeeper to finish. It was the only one of his four shots on the night to end up on target and he was flagged offside three times.

Both of Lewandowski's offsides cut short goal celebrations, and he scored one from two shots. It would be a brave man who backs against the prodigious Haaland reaching those levels of efficiency sometime soon. He will be a truly terrifying prospect.

However, Dortmund's wearying experience suggests, like Lewandowski before him, Haaland will be playing somewhere else by that stage. The same can probably be said for Sancho, Reyna and Bellingham when they fully realise their vast talents.

Such is a reality where a bolted down defence and livewire attack can only mean BVB take some sharpened, shiny knives to the Klassiker gunfight.