Pellegrino received warm cheers as he put in a creditable performance against the dominant force in tennis, and he also showed some deft technique when given room to breathe by Sinner.
But Sinner was never in top gear and still comfortably dealt with Pellegrino to set up a clash with 12th seed Andrey Rublev.
Should Sinner win a record-extending sixth straight Masters 1000 title, he will be the first Italian to win at the Foro Italico since Adriano Panatta 50 years ago.
With great rival Carlos Alcaraz out injured and Zverev now gone, Sinner is red-hot favorite for victory as he builds towards completing the career Grand Slam at Roland Garros.
Zverev, the 2024 champion in Rome, slumped in three sets as Darderi rallied to his first ever win over an opponent ranked among the world’s top 10 players.
“It’s my most important win, to beat Zverev at Roma is the most exciting win of my career,” Darderi said.
While Sinner and Darderi — set to rise to a career-high 17th in the world — reached the Last Eight, their compatriot Lorenzo Musetti was not so fortunate as physical problems led to him being beaten 6-3, 6-1 by Casper Ruud.
Musetti was in tears at the end of his third-round win over Francisco Cerundolo and had to take a medical time-out for a problem with his left thigh during the second set against Ruud.
The Italian will drop out of the top 10 of the men’s rankings ahead of the French Open next week, and he later told reporters that he is unsure of whether he will participate in Paris.
Norwegian Ruud is on the other side of the draw from Sinner and will face Karen Khachanov in the last eight after exploiting Musetti’s struggles with fitness.
“I realized that... we try to make him run as much as possible. It’s cruel and it’s brutal, but that’s sport,” Ruud told reporters.
Khachanov, seeded 13th, ended Dino Prizmic’s bid to reach his first Masters 1000 quarter-final, seeing off the spirited Croatian qualifier 6-1, 7-6 (7/2).
Prizmic had announced himself on the big stage this week by knocking out Novak Djokovic in the second round.