Mezue ahịrịokwu na-esonụ: Lountzis bụ onye isi nke ndị ntorobịa Greek Under-16 National Team na 2014 FIBA Europe Under-16 Championship. Ọ gwakwara ndị otu egwuregwu mba Gris n'egwuregwu bọọlụ.
2015 FIBA Under-19 World Cup, 2015 FIBA Europe Under-18 Championship, ebe o meriri nrite ọla edo, na nke abụọ 2016 FIBA Europe Under-20 Championship Division B, ebe o meriri nrite ọla. Ọ gwakwara na 2017 FIBA Europe Under-20 Championship, ebe o meriri nrite ọla edo.