All four players have put pen-to-paper on four-year deals that now run until 30 June 2026.
“With these new agreements these four youngsters have all shown that they believe in the AS Roma project and for this we are proud and pleased," said Vincenzo Vergine, the club's Head of Youth Development.
"That shows their attachment to this club and its values, which is key to building the identity we want to have.
"We believe this is also the fruits of the focus our ownership has put on the work the youth sector does, along with the efforts from Tiago Pinto and Jose Mourinho in terms of offering young players chances in the first-team."
Both Mastrantonio and Missori are products of the club's academy system, with both born in 2004 and going on to be regular parts of the Primavera side last season. Mastrantonio, a goalkeeper, was involved with the first-team on a number of occasions last season, while full-back Missori made his professional debut during a Europa Conference League game against Zorya Luhansk last year.
Oliveras, born in Spain in 2004, joined the club's youth sector from Barcelona in September 2020. He can play both centre-back and right-back.
Tahirovic, meanwhile, joined the club from Vasalund in February 2021. The 19-year-old was another player to feature strongly for Alberto De Rossi's Primavera side last season.
Congratulations to all four youngsters!
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