Robin Hack joined TSG at U15 level and became an U15 Southern Champion alongside Dennis Geiger and Meris Skenderović in 2013. As an U17 player, Hack was in the squad for the final of the 2015 U19 German Championship, which Hoffenheim lost 3-1 to Schalke, but he didn't feature in the match. He made his comeback from a tibia and fibula break in the 2016 final after missing the 2015/16 whole season, but TSG lost 5-3 to Dortmund. Born in Pforzheim, Hack has played for Germany's youth teams since U16 level and, like Geiger, is part of the Germany’s squad at the 2017 European U19 Championship in Georgia. He debuted for TSG's first team in October 2017 and scored an early goal in his very first match.