WATCH the ATP Tour LIVE in Australia on beIN SPORTS | Subscribe here and take advantage of our 7-day FREE TRIAL

Sinner's run of 30 consecutive victories at ATP-level events – the longest by any player on the ATP Tour since 2011 – was halted in remarkable circumstances on Friday (AEST).

Having claimed the first two sets with relative ease, Sinner went 5-1 up in the third and was a game away from the third round, having also cruised past Clement Tabur in straight sets in round one.

However, the world No.1 then started to show effects of feeling unwell, repeatedly suggesting his legs were cramping up and he was close to vomiting.

Cerundolo won six straight games to take the third set, then cruised through the fourth and the fifth, winning seven games to love in total, with Sinner hardly moving in many of those.

In the last 20 years, Sinner is only the second No.1 seed to lose in the round of 64 of a grand slam men's singles draw, after Rafael Nadal at the 2023 Australian Open.

Hot weather has been a factor at this year's French Open, with the temperature hitting 35 degrees celsius, one day after Jakub Mensik collapsed on court after a victory over Mariano Navone.

But Sinner says that was not the primary factor for his defeat, which means a run of nine straight grand slam titles being won by either the Italian or his rival Carlos Alcaraz will end next week.

Asked when he started to struggle, Sinner said: "The middle of the third set. Even though I was playing some great tennis, I really couldn't find any energy today.

"It was a tough spot to be in. But, again, this is the sport. It was warm but not crazy warm. I feel like it was okay to play in.

"Really it was nothing against the heat, nothing against the weather. It was just me today, but it happens.

"I struggled and started to feel very dizzy, very low on energy. I tried to serve it out but didn't have a lot of energy. 

"In the fourth set, I let it go a little bit, trying to have a bit more energy in the fifth. The first one was a very important game and I couldn't hold. Then it went a bit downwards.

"I woke up this morning, I didn't feel very well and tried to keep the points very short. In the beginning, I was hitting very cleanly, and then I just kind of hit the wall, and that's it."

Sinner's early exit from the clay-court slam comes after he won all three ATP Masters 1000 events on the surface, in Monte-Carlo, Madrid and Rome.

The Italian is only the second player to accomplish that feat in a single season, after Rafael Nadal did so in 2010, and he believes his year has been an overall success thus far.

"I always try to look on the positive side. If you watch the whole clay swing, it went very well," he said. "I played really well, winning three tournaments in a row on clay.

"Coming here, with how I was playing, I felt very well, hitting the ball in a good way, moving well and today was just not meant to be.

"I think many things together caused this problem today, but again, it can happen.

"I just need my time now to process what went wrong here, and also the positives that we can put in good practice in the weeks before Wimbledon.

"After Wimbledon, we have important tournaments coming up – there are still plenty to play this year."