Tuhia he haere tonu mo tenei waahanga - I te tau 2017, ko Mastromatteo tetahi o nga roopu koura i wini i te 4x100 medley whakauru i te 2017 World Junior Swimming Championships. I te tau 2019, i wini a Mastromatteo i nga mētara e 3 i te 2019 World Junior Swimming Championships
i Budapest, tae atu ki te mētara hiriwa takitahi i te 50 mita i te whitiki.