In theory, RB Leipzig’s players should have acclimatised to being the most widely loathed team in German football: over the past five years the club, owned and run by the Austrian energy drink giant Red Bull, has climbed through the lower leagues to its current position near the top of the second division, and the boos and jeers from opposing fans have got louder and louder.

And yet it seems they still weren’t prepared for what happened on Sunday: when Leipzig’s first XI entered Union Berlin’s Alte Försterei stadium at 1:30pm, they were greeted with 15 minutes of silence from the 20,000 spectators, clad almost entirely in black.

With permission from Union’s management, fans had handed out black plastic ponchos at the gates, along with a pamphlet headlined, “Football culture is dying in Leipzig – Union is alive”.

“Today’s opponent embodies everything that we at Union don’t want from football”, it read. “A marketing product pushed by financial interests […], players with euro signs in their eyes […], supported by brainwashed consumers in the stands who have never heard anything of fan ownership”.

A banner inside the stadium stated: “Football needs workers’ participation, loyalty, standing terraces, emotion, financial fair play, tradition, transparency, passion, history, independence.”

In sporting terms, at least, the protest worked. Thanks to two goals from Sebastian Polter, Union Berlin won 2-1 – their first win of the season lifting them out of the relegation zone. It was RB Leipzig’s first defeat, dropping them into third place. As the Berlin club’s anthem “Eisern Union”, sung by punk icon Nina Hagen, rang through the stadium, it didn’t seem too absurd to dream that people power might halt the run of big business on German football.

On the surface, the two clubs from the former East could not be more different. Union, founded in 1966, is frequently cited as the shining example of what you get when fans have a say in how the club is run. This summer, it invited its supporters to bring sofas into the stadium to watch World Cup matches on a giant screen. In 2009, 1500 fans volunteered to help with renovation works at the home ground in Berlin’s Köpenick district.

RB Leipzig was created by Red Bull in May 2009 and has enjoyed generous funding from the company’s billionaire owner Dietrich Mateschitz ever since: this summer alone, it invested almost €12m in new players.

Unlike Union, the Saxon club is accused of resisting supporter influence, deliberately making fan membership expensive and hard to obtain. A proper membership scheme was introduced only when the German football league threatened not to hand Leipzig a second-division licence this summer. It now has around 300 members. Union have 12,054.

Union have not been shy to criticise their Leipzig rivals in the past. When the club were trying to attract investors in 2011, they ran an ad showing a crushed can of Red Bull, with the slogan, “We are selling our soul, but not to anyone”. That same summer, the Berliners set a precedent by cancelling a friendly against Leipzig in response to fan protests – bigger Bundesliga teams such as Stuttgart and Nuremberg have since followed suit.

When Bochum’s coach Peter Neururer recently said that what Red Bull were doing to football “makes me want to throw up”, he seemed to speak on behalf of fans across the country, concerned that the success of the Leipzig model could hollow out the community-minded principles of German club football. “When football is predominantly used as a marketing unit for a brand of product,” Neururer said, “then I can understand the fans’ concerns.”

Yet in reality, RB Leipzig’s supporters say, things are not as simple as the contrast with Union suggests. The rise of the Roten Bullen, they argue, needs to be understood within the context of the decline of East German football after the fall of the Berlin wall. While the traditional GDR-era clubs Lokomotive Leipzig and Chemie Leipzig have perished, RB looks like a club with a future.

Red Bull’s money has helped build the kind of modern training facilities the region had been missing for years, with the sporting director Ralf Rangnick stating he wants “every young talent in the east to run through our professional academy”. The club already has a track record of selecting young players, such as the Denmark international Yussuf Poulsen (20) and the U19 European champion Joshua Kimmich (19), over seasoned veterans.

In the long run, the East German football expert Frank Willmann recently suggested, only Red Bull would have the financial acumen to stop Bayern Munich, the juggernaut of German football, from total domination – Dortmund, Leverkusen and Schalke would beg to differ, of course.

In one respect, at least, the pamphlet handed out in front of the Alte Försterei is off the mark. Contrary to what the “plastic club” image suggests, RB Leipzig have a relatively large and loyal support base – last season, it had the highest average attendance in the third division.

One supporters group, the Rasenballisten, released a manifesto which doesn’t sound too dissimilar to the one handed out in Berlin on Sunday: “We offer all those a permanent home at RBL who value the positive sides of the club which is currently enjoying most success in Leipzig, but who nonetheless struggle to identify with a product. The Rasenballisten stand for football, Leipzig and fan culture, not for sponsors!”