Lengkepan kalimah di handap ieu: Stamatis mangrupa anggota tim nasional junior Yunani. Kalayan tim nasional junior Yunani, anjeunna maén di sababaraha turnamén ieu: 2011 FIBA Éropa U-16 Championship, 2012 FIBA Éropa U-16 Championship, 2013 FIBA Éropa U-18 Championship, 2014 FIBA Éropa U-18 Championship. Manéhna ogé maén di
2015 FIBA Under-19 World Cup, 2015 FIBA Europe Under-20 Championship, jeung 2nd division 2016 FIBA Europe Under-20 Championship Division B, di mana manéhna meunangkeun medali perunggu.