The recent rise of Borussia Dortmund in World Football has been a breath of fresh air to die-hard and neutral fans alike. From the grasp of bankruptcy to the finals of football's greatest tournament, Dortmund have risen to the top of European football with the most modest of means.
At the heart of this success is head coach Jurgen Klopp; the charismatic leader of this young gang of skillful players. From tactically astute manager to baffling cheerleader, Klopp is the beating heart of Dortmund, and the reason behind all its success.
Yet the key to Klopp and Dortmund's success is the coach's fantastic eye for talent, and his ability to unearth local gems at a fraction of the costs of his competitors. This is what has made Dortmund so good, in such a short space of time.
Click "Begin Slideshow" for a roundup of the five most inspiring transfers from Jurgen Klopp while at Borussia Dortmund.
Perhaps the most significant player in the recent power struggle between Dortmund and the ever-present power of Bayern Munich is the young centre back Mats Hummels.
Brought up and developed in the red of Munich, Hummels was a young defender with little promise at Bayern before being offered a rare loan deal to Dortmund. After impressing Klopp with his performances alongside Neven Subotic in the heart of defence, the two clubs settled on a deal just short of £4 million.
Over the next five seasons, Hummels would integrate himself in to Dortmund's cause and form a partnership with Subotic that would go on to break records for the least amount of goals allowed in a Bundesliga season.
Upon the acquisition of Mats Hummels, Jurgen Klopp was able to stage his offensive on Bayern.
Now regarded as one of the most comprehensive defenders in the World, Hummels offers Dortmund and Germany a rare gift in astute defending as well as creative passing from the back line. As we've seen countless times in the past few seasons, the difference between Dortmund resorting to stoke-like long balls and the short passes, that liken them to Barcelona. come from the man who starts every play with a daring through ball from the back: Mats Hummels.
At £3.6 million, Dortmund's minor investment was Bayern's ultimate loss.
The role of a full-back is often considered one of the most unconsidered positions in football, despite the incredible importance the player plays in the modern game.
Barcelona wouldn't be Barcelona without Dani Alves, Chelsea wouldn't be Chelsea without Ashley Cole, and Borussia Dortmund certainly wouldn't be Borussia Dortmund without Lukasz Piszczek.
In much the same manner as Mats Hummels' own career, Piszczek arrived at Dortmund for relatively little (for absolutely nothing in fact) and would go on to establish himself as one of the best across the World.
Where the young full-back truly strives is in his ability to completely dominate an entire wing when both defending and attacking — in much the same manner as his aforementioned colleagues at Barcelona and Chelsea — and in his link up play with the inside forward before him (usually his fellow Polish international Jakub Blaszczykowski).
One unfortunate method of coherently establishing just how quietly brilliant the young Pole may be, is by comparing him to his fellow full-back on the other wing — Marcel Schmelzer on the left hand-side — and contrasting just how often he makes an error which leads to a goal. The German left-back is awarded critical column space in newspapers every week, while Piszczek quietly gets on with his game.
Since his arrival in 2010, Lukasz Piszczek has modestly transformed into one of the most impressive fullbacks across the continent. Not bad for a free transfer, Mr Klopp.
Although the current wave of opinion regarding this particular player is somewhat negative and condescending in his regard for Borussia Dortmund, it cannot be forgotten just how fantastic a signing Robert Lewandowski was when Jurgen Klopp sought him out in 2010.
Unsurprising to most, Robert Lewandowski has always been a fantastic goal scorer at every club he's played for. At Znicz Pruszków, his goal-to-game ratio was 0.6, at Lech Poznań it was 0.5, and at Borussia Dortmund over the past three seasons it has been 0.53.
An impressive number when we consider that the Polish striker was far from favored at Dortmund initially. In his first season, he featured regularly in the side as a backup to Lucas Barrios, but failed to reach double figures in his debut Bundesliga season. It was only once the Paraguayan striker picked up a long-term injury that Lewandowski was offered the opportunity to shine and become the world-class player we know today.
Of course it would be a great injustice to define Lewandowski as simple a "goalscorer."
What he offers Dortmund — and any potential suitor outside of Munich — is a complete forward who can run at defenders as comfortably as he can play with his back to goal. In the age of the false number nine, Robert Lewandowski represents the goal-scoring directness of an old-fashioned striker, mixed with the athleticism and technique of an inside forward.
At £4.1 million, Jurgen Klopp and Dortmund have already surpassed their moneys worth with this striker.
When Marco Reus announced in January 2012 that he would be joining Borussia Dortmund after the Bundesliga season, seismic shifts rattled through German football. Although perhaps the most obvious and recent inclusion in this list, Marco Reus is truly the most iconic transfer in Borussia Dortmund's modern history.
The German prodigy ,who chose Dortmund over Bayern Munich, is arguably the most exciting prospect in German football at the moment. As we saw in the European Championships in 2012, and the following Bundesliga season that has just concluded, Reus is a young player who cherishes every challenge in front of him, and excels spectacularly.
With 19 goals to his name this season — only two less than his tally for Gladbach in his inaugurating Bundesliga season — Reus has established himself within Dortmund's starting 11, and quickly made himself indispensable to their success.
Of course, the best is yet to come from this young midfielder, and with Mario Gotze's exit looming, next season will possibly prove to be Reus' most important yet. As we briefly saw in the Champions League final, he'll become the priority playmaker at Dortmund, with the responsibility of continuing his role in German football with bright, attacking football.
Despite the large fee of £15 million, Jurgen Klopp dealt a killer blow to Bayern Munich with the acquisition of Marco Reus, in ensuring that the country knew that their recent success wasn't a blip, but the announcement of established, sustainable challenge to the Bavarian stranglehold on German football.
If Jurgen Klopp can be considered the marquee manager on the sideline, guiding this club to greatness, then Marco Reus is surely his equal on the pitch as they characteristically wrestle success and trophies from their Bayern rivals.
Born in Gelsenkirchen from Turkish parents, İlkay Gündogan represents a bright, new form of the German footballer in more ways than most would notice.
A central midfielder signed from 1. FC Nuremburg in May 2011, it has taken the 22-year-old player just two years to go from potential to sheer success. From relegation battles to the final of the European Champions League.
His ability as a player is summed up in the nature of how quickly he has established himself at Borussia Dortmund. Not just in the manner in which he has came in to the squad — like Hummels, Reus, etc — but in demanding his very own spot and role. No player before him quite played the role that he plays now. His position was invented to harbor his excellence.
It's a transition that Dortmund were only too happy to make, and it's one that the German national team are undergoing at the moment. Don't be surprised if you see the young Dortmund midfielder hemmed in beside Bastian Schweinsteiger next summer in Brazil. And don't be surprised if he one day replaces the Bayern Munich midfielder altogether.
What makes Gündogan so impressive is the irregular nature of his genius on the pitch. He's not quite a defensive midfielder and he's not quite an attacking one either. He's something in between without falling under the cliche of a 'box-to-box' midfielder.
His tenacious closing down and transition from defense to attack is the definition of what Jurgen Klopp's Dortmund have always aimed to do with a football. The long-lost son of Klopp's coaching philosophy has finally returned home to claim what is his.
After finishing only his second season at Dortmund, he is without doubt one of the most important players in this squad. He is arguably the most promising.
Just under £5 million is what Jurgen Klopp paid for İlkay Gündoğan's services two years ago. For Klopp and Dortmund he's now worth so much more than a simple number on a piece of paper.