It is a grey morning in Dortmund.

Autumnal rain falls from the sky, orange leaf mulch coats the slick pavements and the wheels of the vehicles thundering past on the Rheinlanddamm send spray fizzing into the air. But inside the Borussia Dortmund offices, housed in a modern, six-storey grey-brick building southwest of the city centre, the mood is as bright as the bold shade of yellow that adorns the club crest.

The previous evening, at a fervent Signal Iduna Park, Dortmund stormed back from 2-0 down at half-time to beat Inter Milan 3-2, keeping their hopes of progressing from the UEFA Champions League group phase in their own hands.

Achraf Hakimi was Dortmund's saviour, scoring the goal that halved Inter's lead and then tucking away the home side's 77th-minute winner, and his starring role in the night's events is of particular satisfaction to the club's chief scout, Markus Pilawa.

Hakimi was 16 and making his way through Real Madrid's youth setup when Pilawa first started watching him. Although some members of Dortmund's scouting department expressed reservations about the Moroccan youngster's defensive qualities, Pilawa was transfixed by his pace and courage on the ball.

The process of recruiting Hakimi was long and painstaking. Dortmund's scouts watched him for three years as he progressed through Madrid's youth teams to the reserve side and first team. There was regular contact with his agent, Alejandro Camano, who was asked to keep the club abreast of his client's plans.

In June 2018, Pilawa went to Geneva with Lucien Favre, who had been appointed Dortmund's head coach a couple of weeks previously, to watch Hakimi play for Morocco in a FIFA World Cup warm-up game against Slovakia. Sitting alongside each other in the stands at Stade de Geneve, the pair discreetly conducted a running commentary on Hakimi's performance, weighing up the pros and cons of taking a punt on the gambolling right-back. A month later, he signed for Dortmund on a two-year loan deal.

Hakimi's first season in the Ruhr valley was not without its difficult moments, but when trusting young players is part of your club's DNA, that simply comes with the territory.

"Last season, there were three or four games in a row where he made big mistakes that cost a lot of points," Pilawa tells Bleacher Report. "But I expected it. If you sign young players, they don't have full quality in every skill. You have to know that there will be some games where it will cost you points. But you make a balanced evaluation. It's risk and reward."

Dortmund have taken risks with a succession of promising young footballers over the past 15 years, and the rewards have been considerable.

As is so often the case, necessity was the mother of invention, with Dortmund's near-bankruptcy in 2005 obliging the club to clear high-earning, experienced professionals from the books and promote young players to take their place.

Jurgen Klopp's penchant for fast, high-energy football meant that he was more than happy to work with a youthful squad following his appointment as head coach in 2008, and together with Dortmund's former chief talent-spotter, Sven Mislintat, and sporting director Michael Zorc, they built a team that won back-to-back Bundesliga titles in 2011 and 2012 and reached the Champions League final in 2013.

Dortmund's policy of signing young players cheaply, giving them first-team exposure and then selling them on for massive profits has made the club a byword for transfer success, with Shinji Kagawa, Ilkay Gundogan, Pierre-Emerick Aubameyang, Ousmane Dembele and Christian Pulisic just some of the players to have trodden that particular path in recent years.

In turn, the lure of regular playing time, Champions League football and a consistently full, vibrant stadium has turned Dortmund into one of the most attractive destinations in Europe for the game's leading young talents.

"I knew what to expect when I signed here," Dortmund winger Thorgan Hazard told Bleacher Report after the win over Inter. "It's a team that's used to playing in big matches, going far in the Champions League and competing for the Bundesliga. It was for matches like this that I decided to join."

German football journalist Uli Hesse, author of Building the Yellow Wall: The Incredible Rise and Cult Appeal of Borussia Dortmund, calls Dortmund's approach to recruiting young players "a self-fulfilling philosophy."

Zorc has described Dortmund's attempts to keep pace with Europe's big-spending super clubs as being like a Ford Mustang trying to overtake a Ferrari. But although Dortmund continue to clock impressive speeds, narrowly failing to pip Bayern Munich to the chequered flag in the Bundesliga last season, rival teams have figured out what is going on beneath their bonnet and are replicating the engineering for themselves.

As clubs around Europe look to ape the Dortmund model, the market for young footballers has become more competitive than ever. It is moving scouts such as Pilawa to look at talented 15- and 16-year-olds not as promising prospects but as players who might be first-team ready in only one or two years' time.

"There is a big, big hype for 16-year-olds," he says during an interview in an airy meeting room on the third floor of the Dortmund offices. "One-and-a-half years ago, a 16-year-old guy [Pietro Pellegri] went from Genoa to Monaco for €25 million. Sixteen and a half years old.

"The battle for young talent is incredible, and in the next few years it will increase. Signing players at the age of 16 will be a big, big fight, because you know once they reach 20, a lot of clubs will not be able to pay the fees for them.

"Players who are 20 years old like Matthijs de Ligt or Frenkie de Jong, you can't afford them at Borussia Dortmund. They cost €70 million to €100 million. Joao Felix, €125 million. [Bayer Leverkusen's Kai] Havertz will also be over €100 million. Even Bayern Munich are struggling with fees of €100 million."

Faced with the increased competition for young players, Dortmund are investing, beefing up their video scouting department and spending €20 million to renovate the club's Hohenbuschei training facility in the Brackel district east of the city centre. The need to think outside the box, meanwhile, has prompted the club to focus more resources on relatively unexplored player markets in the United States and Asia to try to find the next Pulisic or Kagawa.

There are high hopes for Gio Reyna—son of former United States internationals Claudio Reyna and Danielle Egan Reyna—who joined Dortmund from New York City in July. In an example of the careful manner with which Dortmund ease their young players into first-team action, the 17-year-old attacking midfielder has been playing with the club's under-19s while he adapts to his new surroundings (and attempts to get to grips with the language) but is due to be promoted to the senior squad for their winter training camp in Marbella.

As with all of Dortmund's young players, Reyna has been following a detailed career development plan from the moment he signed. The document outlined what opportunities he would be given to train with the first team, when he could expect to be promoted to the first-team squad, what positions he would be asked to play in and even who his rivals for a starting place would be.

Mindful of the potential value of their teenage recruits and conscious of the huge psychological pressures that exist in the modern game, Dortmund have also moved to place greater emphasis on the pastoral care that their young players receive.

Former Dortmund midfielder Otto Addo was recruited from Borussia Monchengladbach in April this year to work as a talent coach, offering technical coaching support and ad hoc advice to players from the first team down to the under-16s. Oddo will meet players for informal dinners, take them through video analysis sessions, arrange extra training exercises on certain aspects of their game and advise them on their career plans. Pilawa says he is like "a friend, father and coach."

While youth will always be central to the Dortmund project, recent transfer windows have revealed a more pragmatic edge to the club's recruitment strategy. Experience was the order of the day in the summer of 2018, with seasoned holding midfielders Axel Witsel and Thomas Delaney the headline acquisitions, and that trend continued this year with the captures of 26-year-olds Hazard and Nico Schulz and, in particular, the return to Dortmund of 30-year-old centre-back Mats Hummels. The fearlessness of youth, it seems, can only take a team so far.

"Dortmund cannot be on an international level what Freiburg are on a national level," Hesse says. "They cannot be content with just nurturing young players and then selling them on for a profit. Because they want to win things. Dortmund want to win a trophy, and you probably can't do that with kids alone. That seems to be the lesson the club has learned."

The moves to bring in more experienced players reflect an acknowledgement behind the scenes at Dortmund that the squad's age profile was imbalanced, yet Pilawa says it would be wrong to see it as an abrupt change of direction. Older players like Hummels and Witsel will obviously bring know-how and a winning mentality to the first team, but they will also help to establish standards towards which their younger team-mates can aspire.

"It's very important to put in some experienced guys to lead the young players," explains Pilawa, who joined Dortmund from local rivals VfL Bochum in 2012. "We want to be champions, for sure, but our fans expect to see young players like Jadon [Sancho] and Hakimi because it's the DNA of the club. We try to combine it. Sometimes we put Mats Hummels in. Maybe next year it's Gio Reyna. We are not changing our philosophy. It's all about the structure of the team."

There would be even more youngsters clamouring for a place in the first-team squad were it not for the fact that the Dortmund academy is no longer turning out elite-level players at the rate it once did. Whereas Klopp's great Dortmund team featured home-grown stalwarts such as Mario Gotze, Nuri Sahin and Marcel Schmelzer, the production line has since slowed, meaning that most of the youthful talent in the squad has been imported from elsewhere.

Pilawa believes it is a "German problem" rather than something specific to Dortmund, expounding a theory that Germany has fallen behind countries such as England and France at youth level partly due to an absence of multi-ethnic football breeding grounds comparable to south London's cage football scene or the Parisian suburbs.

Youssoufa Moukoko, a 15-year-old Cameroonian-born striker who has been scoring goals for fun for Dortmund's youth teams, is one player on the club's books who has been earmarked to buck the trend.

"We're discussing in Germany what the problem is," Pilawa says. "Maybe we were focusing more on tactical things to develop the team and maybe not the individual player. Maybe we neglect the individual something that a Jadon Sancho or a Hakimi has. Hakimi is a team player, of course, but he's got something that you can't control. We haven't taught this certain something enough.

"In the next few years, it will be a big, big goal for us to change that and send a young Dortmund guy from the youth team to the first team."

The week of the victory over Inter ends with a one-sided 4-0 hammering at Bayern that leaves Dortmund six points off the pace in the Bundesliga title race and brings everyone at the club back down to earth. But away from prying eyes, in the club offices, in training-ground meeting rooms and on the pristine green pitches of the academy, the future is already taking shape.