In a clash of US Open champions, Coco Gauff outclassed Emma Raducanu 6-1, 6-2 charging into her third Rome quarterfinal.
Alcaraz has now won 23 of his last 25 on the red clay.
Draper, Musetti and Zverev hit their numbers on Sunday in Rome.
Aryna Sabalenka rallied past Sofia Kenin 3-6, 6-3, 6-3 to score her eighth straight win and set up a rematch with Marta Kostyuk in Rome.
Sinner sparkled at times, and fought at others, as he returned from his suspension with a win.
Danielle Collins broke serve six times dismissing defending champion Iga Swiatek 6-1, 7-5 to power into the Rome round of 16.
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