Borussia Dortmund CEO Hans-Joachim Watzke has taken a sly dig at the club's European rivals, claiming that the Bundesliga side don't have a "Russian, or Arab, or Chinese investor throwing €50m at us every year".
BVB struggle to compete financially with league rivals Bayern Munich, but have maintained a sound financial structure by selling established players and replacing them with stars of the future.
Watzke has admitted that such a method is difficult, but stressed the importance of the club sticking to their principles.
"The important thing when investing the money we earned in order to step up, was to not spend more than we earned," he said in an interview with JPN Sports Digest, quoted in Reddit. "This is a very important policy for Dortmund.
"It is important because we must do all the work ourselves. We don't have a Russian, or Arab, or Chinese investor throwing €50m at us every year, and we don't want one. So, we don't spend more than we earn. It's simple, but also difficult.
"Every club has their method. Invest in star players, win titles? That is Real Madrid's method. Dortmund's method is to obtain players with great potential, like Dembele, Pulisic, Kagawa seven years ago. And we develop them.
"We are doing well financially, but not as well as Manchester United or Real Madrid. But we have succeeded with our method.
"We are ranked seventh in UEFA, above both Manchester clubs and Liverpool. Last summer, we sold Mkhitaryan, Gundogan, Hummels for €107m. We spent €100m on signings, but not on one Ronaldo. Instead, we signed a Dembele who will play like Ronaldo in three years.
"Before breaking out with us, how many knew of Aubameyang? Lewandowski? Nobody knew about them. But now they are global stars. We've fought Madrid with our method, and won many times."
Watzke added that this well established and well organised method was born out of necessity when the club were in financial dire straits, although it has proved an undeniable success.
"Twelve years ago, we were on the verge of bankruptcy," he added. "When you are broke you cannot say, let us sign this player for €30m. You don't have the money.
"Also, Dortmund has never in the past, been as strong as Bayern, or Madrid. Dortmund is a small city, with a population of 600,000. We don't have the foundations Madrid has.
"Our current situation, is more than enough. Ten years ago, who would have predicted Dortmund would be earning €400m? But we do. Dortmund is no longer broke, and we have not one single euro of debt. From that perspective, this method is the right method."