Men's world number one Sinner was cruising when leading by two sets and 5-1 in the third set before suddenly struggling with his movement as he lost 18 points in a row.

Sinner took a medical time-out, complained of feeling "dizzy" and left a sweltering Court Philippe Chatrier for treatment, but after returning still slipped to a 3-6, 2-6, 7-5, 6-1, 6-1 second-round loss to world number 56 Cerundolo.

"I struggled, starting to feel very dizzy. Very low of energy. Tried to serve it out, but didn't have a lot of energy," said the Italian.

"Woke up this morning, didn't feel very well and tried to keep the points very short."

Sinner suffered his earliest exit from a Grand Slam since the 2023 French Open, as Cerundolo completed one of tennis' biggest shocks in recent years and set up a last-32 tie against Spanish youngster Martin Landaluce on Saturday.

The 24-year-old Sinner was the latest player to wilt under the blazing sun this week, seeing his 30-match winning streak, after taking titles in Rome, Madrid and Monte Carlo, Miami and Indian Wells, come to a shuddering halt.

The Italian will now have to wait until next year, when injured rival Carlos Alcaraz will likely be back in action, for his next chance to complete the career Grand Slam.

The top seed was in total control and romping towards the most routine of victories before he suddenly started to struggle physically, losing three consecutive games to love.

He asked the chair umpire what his options were when 0-40 down in the next game, before being evaluated by a physio, saying he felt dizzy and needed to vomit.

Sinner gingerly returned to the court after treatment to applause from the crowd but continued to melt in the 32C heat as Cerundolo took the set.

Unheralded Argentinian Cerundolo appeared inspired by the unexpected opportunity and raced to victory against his deflated opponent, who was left bent over double after every lengthy rally.

"I was little bit lucky, I feel sorry for him," said Cerundolo, whose older brother Francisco also booked a last-32 spot shortly afterwards.

French 17-year-old Moise Kouame became the youngest man to reach the third round at a major since Rafael Nadal at Wimbledon 23 years ago.

The wildcard delighted a raucous crowd with a dramatic 6-3, 7-5, 3-6, 2-6, 7-6 (10/8) over Paraguay's Adolfo Daniel Vallejo after four hours and 56 minutes on Court Suzanne Lenglen.

"Frankly, without you, I would never have won this match, never," Kouame told the crowd.

Canadian fourth seed Felix Auger-Aliassime reached the third round for only the second time in his last eight Grand Slam events, beating Roman Andres Burruchaga in four sets.