For someone who lived off a diet of rice pudding and frozen pizzas not so long ago, the 24-year-old's rise to become a member of the senior Germany squad less than two years after plying his trade in the German third division is nothing short of remarkable.
Like many youngsters of his age, the Niedersachsen-born winger dreamt of the big time when he penned a contract with Hamburger SV in 2008 at the age of 17. However, his professional debut proved elusive to begin with and it was in the northern German club's reserves that he simultaneously planned for a career as a car-body painter.
Hahn juggled working alongside his training commitments but even his fierce dedication was not enough to earn him a place in the HSV first-team squad. "They said I wasn't going to make it," he told kicker magazine. "Nobody, absolutely nobody believed in me, apart from my father and myself."
Fourth-tier outfit FC Oberneuland eventually offered Hahn a contract in 2010 and he admitted he "really had to beg them" to take him on. It was a far cry from the glamorous life one has come to expect from professional footballers, though: "I often had to get by with three frozen pizzas and a rice pudding during the week. It really wasn't a great life."
Seven goals in four matches later, however, and Hahn was snapped up by third-division TuS Koblenz. He soon moved on to league rivals Kickers Offenbach, where he went on to make 44 appearances in two years. Then, much to his own surprise, Hahn received a phone call from FC Augsburg's sporting director Stefan Reuter. "I was stunned. Lost for words," he recalled.
It was a call that changed Hahn's life. Two days after joining the Fuggerstädter during the 2012/13 winter break, he made his Bundesliga debut. Only a year later, having led the scoring charts for FC Augsburg in 2013/14, his incredible story became enriched with yet another glittering chapter when Germany assistant coach 'Hansi' Flick invited Hahn, who originally "thought it was a wind-up", into Germany's pre-World Cup squad.
He earned his maiden full international cap in a friendly against Poland in May 2014 and although he narrowly missed out on a place in the country's final ensemble in Brazil, his dazzling performances throughout the 2013/14 campaign convinced Gladbach to secure his services to aid their efforts to improve on a sixth-placed finish that season.