Musetti and American Frances Tiafoe took to the main show court next and it was the Italian who mastered the breeze to continue his brilliant clay court season with a 6-2, 4-6, 7-5, 6-2 result. Musetti now has two days to plan for his first RG semifinal on Friday after winning 18 of his last 21 matches on the red dirt.
The night match featured a clay court masterclass from defending champion Alcaraz who blew away another American Tommy Paul 6-0, 6-1, 6-4 in what was the Spaniard's best performance of the tournament so far.
The big story across the wheelchair draws was a first round defeat for four-time Roland-Garros defending champion Diede de Groot as the Dutch legend lost to China’s Li Xiaohui 6-2 6-4 on Court 13.
Third seed De Groot brought a 52-match winning streak at the majors into Paris - it was her first singles defeat at a Grand Slam since 2020 at Roland-Garros.
Another four quarterfinals take centre stage on Wednesday with Americans Coco Gauff and Madison Keys meeting at 11am.
Dan Imhoff chatted to former US Open champion Flavia Pennetta about Keys’ first major win in Australia in January, with the Italian drawing comparisons to her own surprise Grand Slam title in New York in 2015.