'Without fans, the players have to squeeze out of themselves the same qualities that turned them into Bundesliga professionals.'
When Borussia Moenchengladbach met neighbours Cologne in the Bundesliga's first-ever game without fans back in March, even the referee missed the crowd.
"Football has lost half its value," said Deniz Aytekin - despite being spared the customary abuse from the stands.
Since then, it has become increasingly clear that football will have to be played behind closed doors until a major change in the course of the coronavirus pandemic - and that some creativity will be needed to provide a little atmosphere.
From cardboard cut-outs of real fans to an app allowing supporters to influence the volume of noise piped into stadiums, people are developing ideas for how to put some matchday atmosphere back into the stadiums -- though whether their ideas are accepted is a different matter.
In Belarus, the only European league to plough on through the global health crisis, Dinamo Brest filled the stands with mannequins sporting cut-out portraits of real supporters.
Moenchengladbach will follow suit when the Bundesliga becomes the first of Europe's major leagues to restart on Saturday.
For 19 euros, the club offers to put a "cardboard you" in the stands - and visiting teams' fans can book cut-outs for the away end. The club said more than 12,000 such effigies have been ordered so far.
"The campaign organisers are regularly overrun with orders," said Gladbach fan representative Thomas Weinmann.
But for many, the real problem of "ghost matches" is the lack of noise and eerie atmosphere with the shouts of players and coaching staff echoing around deserted arenas.
Cologne coach Markus Gisdol suggested this could even lead to frayed tempers.
"Everyone on the sidelines was a little more irritable than usual because you could hear more of what the opposing bench were saying and what the officials were saying to each other," he said after the Moenchengladbach game.
On the other hand, he said the lack of crowd noise would take players "back to their roots."
"Without fans, the players have to squeeze out of themselves the same qualities that turned them into Bundesliga professionals."
One company though - Munich-based hack-CARE - has developed an app which it says produces piped crowd noise based on the reactions of supporters watching on their sofas.
Fans who download its Myapplause app choose which club to support and which match to watch, and then get four options: cheer, clap, sing or whistle.
The app can support up to 350,000 users per match and, depending on the number of clicks and sound distribution, piped crowd noise is produced both at users' homes and in the stadium.
"We tested it in two Bundesliga stadiums, we were live and it went really well," Viktor Mraz, one of the developers, told Reuters. "You press a button and the whole stadium is cheering."
He said talks were underway with all of Germany's big clubs.
"Everybody is talking to us, even other sports," he said. "A lot of people need to agree - the players need to agree, the referees.. - so I guess we will start without any sounds in the stadium," he said.
Mraz added that different sounds could be played in different parts of the stadium and sound levels adjusted to recreate the impression of having home and away support.
"The songs for one team come over the left loudspeaker, the songs for the other come over the right loudspeaker, so you have the separation of blocks like you would usually have in the stadium," he said.
Still, issues remain. Some years ago, Swiss broadcaster SRF apologised for adding fake crowd noise to the highlights of an FC Zurich-Grasshoppers derby where fans boycotted the start of the game over ticket prices.
And the last word may rest with the German Football League, which said it remains "strongly opposed" to the idea of piped noise.
"Our fans can't be replaced by any virtual audience, therefore we strongly discourage our clubs from using any artificial crowd noise," a spokeswoman told Reuters.
"We can't force the clubs not to use it - but we think they got the point."