Tsitsipas needed more than three and a half hours to turn things around and get past 20-year-old Musetti of Italy 5-7 4-6 6-2 6-3 6-2 as the calendar flipped from Tuesday to Wednesday.

"It was a great first round. I'm going to keep working hard to improve and build a relationship with the crowd here," Tsitsipas, who set up a meeting against Czech Zdenek Kolar, said on Court Philippe Chatrier.

"My serve was really off ... maybe not the first few games of the match, but after, it completely collapsed. It wasn't there. That threw me off a lot.

"Once I really found my momentum ... I knew that it can be a different match.

"It would have been kind of not fair, from my perspective, to have a different outcome."

Fourth seed Tsitsipas has not lost in the first round in Paris since his 2017 debut. The 23-year-old from Greece has progressed further each year, getting to the second round in 2018, the fourth in 2019, the semi-finals in 2020, and then losing the title match to Djokovic in five sets a year ago.

Second-seeded Daniil Medvedev though took less than 100 minutes to progress but world No.15 Denis Shapovalov lost to Danish teenager Holger Rune.

Medvedev brushed aside beat an injured Facundo Bagnis 6-2 6-2 6-2 while Shapovalov lost 6-3 6-1 6-4 7-6 (7-4) to Rune, another promising Scandinavian.

Once only Swedes - and plenty of them - figured in the tennis elite from the region. Now there is only 95-ranked Michael Ymer from Sweden in the mens top 100. Above him is a Finn, Emil Ruusuvuori (61) who beat Ugo Humbert 6-2 2-6 6-7 (7-4) 6-4 6-2 to progress, Rune (40) and Norway's Casper Ruud (8).

Ruud was the day's villain, bringing down the curtain on the career of French favourite Jo-Wilfried Tsonga who said he will retire after the tournament.

The 37-year-old took the first set, but by the end the ailing two-time semi-finalist could barely serve as Ruud won 6-7 (6-7) 7-6 (7-4) 6-2 7-6 (7-0).

Gilles Simon's last French Open will continue after a marathon victory over No.16 seed, and two-time US Open semi-finalist, Pablo Carreno Busta.

The 37-year-old Frenchman delayed his retirement for at least another match by winning 6-4 6-4 4-6 1-6 6-4 in a little under four hours.

Simon is a former top-10 player and two-time grand slam quarter-finalist, currently ranked No.158, and needed a wildcard invitation from the French tennis federation to get into the field.

Russian seventh seed Andrey Rublev survived a first-set scare to move past Kwon Soon-woo 6-7 (7-5) 6-3 6-2 6-4.

The 24th-ranked Frances Tiafoe finally earned his first victory at the French after six first-round defeats by beating Benjamin Bonzi 7-5 7-5 7-6 (7-5) and next faces Belgium's David Goffin.

With agencies.

Australian Associated Press