Jannik Sinner's French Open campaign is over after the world number one struggled with illness in a shock second-round loss to Juan Manuel Cerúndolo.Sinner fell to 56th-ranked Cerúndolo 3-6, 2-6, 7-5, 6-1, 6-1 in a result that stunned the crowd in Paris.He failed to serve out the match twice, including at 5-1 in the third set.Cerúndolo claimed 18 of the final 20 games and became the first man to oust the top-seeded player at Roland-Garros before the third round since 2000.Yet to win a French Open, Sinner arrived in Paris as the favourite for the men's title after clay-court triumphs in Monte Carlo, Madrid and Rome.Sinner's main rival and defending champion, Carlos Alcaraz, was ruled out with injury, and Novak Djokovic is searching for his best form.But Cerúndolo tore up the script in a dramatic clash where he held his nerve, as last year's runner-up Sinner crumbled while on the verge of victory."I started to feel very dizzy," Sinner told a packed media conference after the match."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."It was an important game, the first one. 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 short. In the beginning, I was hitting very clean, very good, and then I just hit the wall. That's it."Juan Manuel Cerúndolo accepted the applause of the Roland-Garros crowd.