Tulis a continuation for this paragraph - Dina 2017, Mastromatteo mangrupa bagian ti tim medali emas nu meunang 4x100 medley dicampur di 2017 World Junior Swimming Championships
. tapi Dina taun 2019, Mastromatteo meunang 3 medali di 2019 World Junior Swimming Championships di Budapest, kaasup medali pérak individu dina 50 m breaststroke.