Born in Rome, Mastrantonio started playing football at Urbetevere, before joining Roma's youth sector in 2017, aged 13.[1][2] He subsequently came through the club's youth ranks, winning national titles at under-15 (in 2019) and under-17 levels (in 2020),[1][3] before reaching the final of the under-19 championship in 2022.[4][5] After signing his first professional contract with Roma in July 2021,[6] the following year Mastrantonio renewed his deal with the club until 2026.[7][8]
On 13 July 2022, the goalkeeper was sent on a season-long loan to Serie C club Triestina.[9] He then made his professional debut on 3 September, aged 18, as he started the league match against Pordenone, which ended in a 0-2 loss for his side.[10]
On 26 July 2023, Mastrantonio joined Serie C club Monterosi on a season-long loan.[11] After six months his loan was cut short and on 26 January 2024, he moved on a six-month loan to Pro Vercelli.[12]
On 1 August 2024, Mastrantonio joined Milan Futuro, the newly created reserve team of AC Milan, on a season-long loan.[13] Some days later on 17 August, he started with the under-19 squad on the first match of the season, making some impressive saves at the 4–0 win against the newly Campionato Primavera 1 promoted Udinese under-19 squad.[14]
International career
Mastrantonio has represented Italy at youth international level, having played for the under-18 and under-19 national teams.[15][16][17]
He was included in the under-18 squad that took part in the 2022 Mediterranean Games in Oran, Algeria,[18] with the Azzurrini eventually winning the silver medal after losing 1–0 against France in the final match.[16]
Mastrantonio has been described as a well-rounded goalkeeper with several key attributes, including reflexes, agility, handling and distribution.[3][15][22] A vocal and focused leader of the defense, he has shown his ability both as a shot-stopper and a penalty saver.[3][15]
