Despite the absence of fans, the Berlin derby is still important in the battle for hearts and minds in the German capital. So far, Union are flexing their fledgling muscles over more established rivals Hertha.
On Tuesday morning, Berliners woke up to a flood of blue and white Hertha flags propped up around the city — in parks, along median strips, even outside the Reichstag building.
The club released a slick video showing club employees planting the "Fahnenmeer" or "sea of flags" under the cover of night, on a quest to "win over the whole city."
A nice idea, but one which fell flat with local authorities who set about removing the paraphernalia. One local politician compared it to a Coca-Cola branding stunt, and Hertha could receive a fine.
On the same day, Union Berlin launched a virtual Advent Calendar where they open a different door at the club each day in December, accompanied with a short narrative. Cheesy, as ever, but low-key and endearing.
Two clubs, two strikingly different marketing strategies. And the differences on the pitch are even starker ahead of Friday night's Berlin derby.
Union Berlin are flying. Preseason predictions of a relegation scrap have been blown away — for now — with Urs Fischer's team in sixth and unbeaten since the opening day. Only Bayern Munich have scored more goals.
Sporting director Oliver Ruhnert brought in 11 new players this summer and said goodbye to even more as pragmatism trumped sentimentality — and brought in a healthy €3 million ($3.6 million) profit to boot.
Union wanted to have two solid options in every position ahead of a grueling season, but their trump card has been a man still proudly sporting a dad body (in football terms) after the summer break.
Striker Max Kruse was a gamble in many critics' eyes thanks to his love of the limelight, a penchant for the glamorous and a string of past misdemeanors — including an apparent breach of the German football league's strict hygiene protocol last month.
But the 32-year-old has helped transform Union from long-ball merchants into a more sophisticated outfit that can rely on the Bundesliga veteran's astute tactical mind to create chances with his intelligent movement and vision. Kruse already has six goals and fives assists, and his teammates appear to have elevated their own games.
Union are making a mockery of their underdog status.
On the other side of town, Hertha have struggled to click into gear, losing five of their opening nine games despite heavy investment to the tune of €110 million ($133.8 million) in the past 18 months alone.
A much-improved defensive display in a goalless bore draw with Bayer Leverkusen last weekend was an improvement, but Bruno Labbadia's men are still to win at home.
Nevertheless there is promise in the squad, with youngsters Matheus Cunha, Dodi Lukebakio and loanee Matteo Guendouzi impressing. And a tough start to the campaign — playing all of the top five so far — suggests better times lie ahead.
They'll also draw confidence from their last meeting with Union back in May, when they brushed aside their local rivals 4-0, avenging a heated 1-0 defeat at the Stadion an der Alten Försterei.
But whereas Union's aim this season, just like last season, is simply survival, Hertha have made no secret of their European ambitions. And so far, they're falling short.
By the end of this season, entrepreneur Lars Windhorst will have invested €374 million in Hertha Berlin, via his investment company Tennor. But power struggles have already emerged.
If the calamitous Jürgen Klinsmann experiment set the tone last season, the sense of disunity has continued into the new campaign. While Windhorst appears keen to move more aggressively, sporting director Michael Preetz prefers a more cautious approach.
When former Germany goalkeeper, Tennor adviser and Hertha board member Jens Lehmann declared that the club was targeting European qualification this season, Preetz's response was damning.
"Lehmann speaks for himself and formulates his own expectations or those of the investor," he said. "We [the sporting management] are formulating the goals of Hertha Berlin."
Over in Köpenick, Union don't appear to have that problem. While Union's cult status can irritate rival fans as cliched and insincere, Union supporters are generally united behind their club and officials are singing from the same hymn sheet.
Hertha, on the other hand, have disillusioned elements of their own support with their clumsy PR, chaotic management, hubristic ambitions and cringey marketing campaigns. The idea to distribute flags across the city this week came from an advertising agency, rather than from the club's active fan scene — an important distinction in Germany.
On Friday night, with no fans inside the cavernous Olympic Stadium, those additional narratives won't matter. It will all boil down to 90 minutes on the pitch at the end of which Union could go third in the Bundesliga — at least for a night.
For Hertha, a first home win could finally spark them into life ahead of an easier run of fixtures.
If Berlin is to grow into a true football city, it needs both of its Bundesliga sides, with their contrasting philosophies, to perform — on and off the pitch.