This, the more gnarled of Bundesliga followers would tell you, is the real Klassiker. Years of mere intermittent threats to Bayern Munich’s dominance have made Borussia Dortmund, Germany’s most visible other club and the champions’ most frequent irritants, the default opposition for a showpiece. More than 40 years have passed since Borussia Mönchengladbach were champions for a fifth and as yet final time, an era in which the mantle of top dogs was a real back-and-forth. In the 1970s, Gladbach’s first two titles and last three were split by a Bayern run of three in succession.

It may be way too early to declare a similar state of suspense but something has changed, and not only because the last time Gladbach were top for this long was that 1976-77 season in which Jupp Heynckes, Rainer Bonhof, Allan Simonsen and company swept Die Fohlen to the Meisterschale. Bayern were here and worse at this time last year, trailing Dortmund by nine points. It does, however, feel “different” this time around, as Joshua Kimmich remarked in the corridors of Borussia-Park as Saturday evening drew in.

It was hard to think any other way, or even to think at all, after this whirlwind of an occasion. This was the sort of afternoon on which Bayern’s motto of Mia San Mia – we are who we are – seems meaningful and not just a marketing buzzphrase. Whatever their issues in terms of leadership, personnel and team identity, they always show up for occasions such as this. Having arrived four points behind Gladbach they spent the first half pinning their hosts back, and it was exactly what we expected. Their dominance over Marco Rose’s team continued after the break, until the twists that turned this from an engrossing contest into something which felt even more significant.

The sense of throwback lasted into the night as ZDF, whose Sportschau broadcasts free highlights on Saturday evenings, received a raft of complaints after the presenter Matthias Opdenhövel accidentally let the result slip before the programme started, not realising his microphone was on. The idea that, in late 2019 and with the ubiquity of social media, viewers can genuinely avoid the result of a Saturday afternoon fixture until the evening is a heartwarming one and fed into the feeling of this being a special day, the suspense of which should be fully embraced.

Still, it was one of those rare matches that will continue to bear repeated viewing, even if you know what’s coming – a version of The Usual Suspects among football matches, if you like, offering finer detail and greater nuance on each watch. It was, improbably, Gladbach who ended triumphant after spending most of the match’s first hour hanging on. Their stirring comeback “left a whole region in jubilation”, as Westdeutsche Zeitung’s Achim Müller put it, and the celebrations were full of meaning, even if it’s too soon to talk about pivotal events.

As fans in the Nord Kurve behind the goal celebrated with their delirious players Marcus Thuram, a pest for Bayern all afternoon who had won the late penalty which was the game’s decisive moment, wandered over to the corner flag, put Ramy Bensabaini’s shirt on it and waved it in triumph at the fans.

The pair were both playing in France last season, Thuram’s efforts failing to keep Guingamp up while Bensabaini played his part in the Coupe de France triumph for Rennes. Here, in entirely another dimension of heat and adrenalin, they played crucial roles. Bensabaini’s towering header on the hour from Jonas Hofmann’s corner equalised Ivan Perisic’s opener and wrested his team back into the game. As stoppage time kicked in Thuram, a revelation in his debut Bundesliga season, improbably found another burst of pace to tear behind Bayern’s back line. Javi Martínez stretched and hauled him over, with the referee Marco Fritz pointing to the spot and showing Martínez a second yellow card.

Borussia Mönchengladbach’s Marcus Thuram was a pest for Bayern all afternoon in their Bundesliga match. Photograph: Pixathlon/Shutterstock

As Bayern came to terms with Fritz’s adjudication and struggled to retain their composure, Gladbach had to scrabble to find theirs. It took a reminder from the bench – and specifically the reserve goalkeeper Tobi Sippel – that Bensabaini was the nominated penalty taker. After Breel Embolo missed against Freiburg last week the Algerian defender, a regular and confident spot-kicker in training, volunteered to step up for the next one, not for a second thinking that it would end up being a kick of such magnitude. “I honestly forgot [having volunteered] when it was given,” he said with a smile. The surety with which Bensabaini struck it home defied the confusion. Manuel Neuer read it, but still couldn’t stop it. Gladbach had their sixth home win in a row, and Bayern were beaten.

For Hansi Flick it was “just like last week against Leverkusen”, he told Sky. His team had played well but failed to take advantage. Both Kimmich and Neuer, meanwhile, talked about Bayern having dropped their intensity after they took the lead. “We deserved to take the lead,” said Kimmich, “but then we stopped playing brave football.” Gladbach, on the other hand, rode their luck on occasion but reaped the reward for their show of guts. Rose had thrown on the hero of last week, Embolo, for the midfielder László Bénes just before Bensabaini’s first, and never looked back. “After the equaliser we didn’t try just to manage the game, but to win it,” he said. “Thankfully, the game has two halves.”

The question now becomes whether Gladbach – seven ahead of Bayern but just a single point in front of Leipzig – can do what Dortmund did not last year and maintain the gap until Christmas. That expectations on them have changed so much is more than just a pinch of nostalgia. It is a huge compliment to Rose and Gladbach, and a shot in the arm for the Bundesliga’s present.

Talking points

• Leipzig had been heading for the top until Bensabaini’s late intervention, courtesy of a 3-1 win against Hoffenheim, which wasn’t quite as easy as it looked but Timo Werner took his personal tally to nine in the past five games. The striker also spoke of his aim to “take the momentum into the summer”, hoping to have more of an influence on Euro 2020 than he did in the World Cup.

• It was a good weekend for Dortmund too, leapfrogging Bayern after sweeping aside a feeble Fortuna Düsseldorf 5-0. Playing in an all-black 110th anniversary kit – the limited run of 9,009 replicas sold out in three hours – there were two goals apiece for Marco Reus and Jadon Sancho in a fine tuneup for Tuesday’s Champions League meeting with Slavia Prague, with BVB needing to win and hoping for a favour from Barcelona.

• It’s on again at the bottom after Paderborn’s dramatic first away win at Werder Bremen. Sven Michel’s goal was initially ruled out but then verified by VAR to move Steffen Baumgart’s team off the bottom and within four points of the play-off place.