Lengkepan kalimah di handap ieu: Lountzis ieu kaptén ti junior Yunani Under-16 timnas di 2014 FIBA Éropa Under-16 Championship. Manéhna ogé maén kalawan timnas junior Yunani di
2015 FIBA Under-19 World Cup, 2015 FIBA Europe Under-18 Championship, dimana manéhna meunangkeun medali emas, jeung di 2nd division 2016 FIBA Europe Under-20 Championship Division B, dimana manéhna meunangkeun medali perunggu. Anjeunna ogé maén di 2017 FIBA Éropa Dina-20 Championship, dimana anjeunna meunang medali emas.