The 23-year-old No.8 seed will face defending champion Carlos Alcaraz or Tommy Paul on Friday for a place in Sunday's final.
Tiafoe, the No.15 seed, reached Tuesday's quarter-final without dropping a single set. But he was not quite up to the task against Musetti, a semi-finalist at Wimbledon in 2024, and it showed right away.
Tiafoe missed all eight first serves in his first service game and sent a backhand wide to give Musetti a break and a 2-0 lead. He looked up at his coach, David Witt — who's worked with Venus Williams and Jessica Pegula in the past — and complained about the wind.
The deficit was 3-0 after just 13 minutes. By the time that set was over, 21 of Musetti's 30 points had arrived via mistakes by Tiafoe, nine forced and 12 unforced.
Tiafoe's first break delivered a 2-1 lead in the second, and when he smacked a forehand winner to level the match at a set apiece, he let out a roar and shouted, "Let's go! Let's go!".
During that set, Musetti was warned for unsportsmanlike conduct for kicking a tennis ball that inadvertently hit a linesperson. Unlike most top-level tennis tournaments, which rely on electronic line-calling, there are still humans on court at Roland Garros to decide whether shots land in or out.
However, Musetti did not let the incident affect him as he moved to victory in four sets. He is now 13-4 in his French Open career, and three of those losses came against an opponent ranked No.1 — Novak Djokovic twice, Alcaraz once.
The only way he'll need to deal with the top-ranked man again in Paris is if it's his pal Jannik Sinner standing across the net on Sunday with the trophy in the offing.
Musetti is one of the rare top players using the single-handed backhand, a vintage shot often praised by tennis connoisseurs.
"We are Italian, we are elegant," he joked afterwards.
With agencies
