Giovanni Bartocci stood outside Billie Jean King National Tennis Center on Saturday shouting encouragement - and eventually employing a microphone and loudspeaker - as the Italian dismantled opponent Casper Ruud in straight sets on Court 17.
Four years ago Berrettini was playing a Futures event in Italy and on Wednesday became the first Italian man since Corrado Barazzutti 42 years ago to reach the US Open semi-finals.