The close bond between Borussia Dortmund's players and supporters comes from the club's 'clear and obvious strategy' to develop homegrown players rather than buy superstars, according to their head of youth Lars Ricken.
England star Jadon Sancho, 19, is the best current example of Dortmund's commitment to youth after they signed him from Manchester City in 2017 and promoted him quickly to their first team.
Now Sancho is being linked with a big money move back to the Premier League this summer, with Manchester United, Chelsea and Liverpool all linked with the player.
And Ricken believes this is Dortmund's template for success, as opposed to buying players already established in first-team football elsewhere.
'The way we do things didn't happen by accident, or by coincidence,' former Dortmund midfielder Ricken told the BBC.
'It is a clear and obvious strategy not to buy superstars but to create them.
'Ousmane Dembele and Pierre-Emerick Aubameyang weren't superstars when they came to Dortmund. We developed them to become superstars. It is very important for the club.
'The reason the atmosphere in our stadium is so good is because there is a great identification between the players and the fans. The supporters see it is a gift for them to play in our stadium.'
Dortmund's policy of buying and improving young players is well established, stemming from their financial problems in the first few years of the 21st century.
What started with the emergence of Mario Gotze and Mats Hummels through the club's academy has gone on to include the likes of Dembele, Aubameyang, Christian Pulisic and Sancho.
The first five were sold on for a handsome profit with Sancho, valued at around £100million, set to be the next.
They will likely do the same with Norwegian striker Erling Braut Haaland, who arrived from Red Bull Salzburg during the January transfer window.
And likewise with Giovanni Reyna, the son of former Manchester City and United States midfielder Claudio, who made his senior debut aged 17 last month having skipped the youth ranks.
'When Gio came to Dortmund, we knew he would become a professional player,' said Ricken. 'That was not the question.
'The question was when does he play for the first team. Summer? Winter? Three months? Six? Everybody was sure he would do it.'
Ricken says Dortmund are also very clear in the qualities they are looking for when they sign young talent.
'Technical skills are very important and the quickness and speed of action,' he said. 'Players in our first team are all so fast. It is unbelievable.
'The other thing is the mentality. The loads we put on the players are very high. School, football, national teams.
'This can all take 70 or 80 hours a week. These boys have to be grown-up, focused and disciplined at a very young age.
'We want to try and find the special one. We were quite successful with Pulisic, Gio Reyna and Jacob Bruun Larsen.'