Jannik Sinner’s French Open campaign ended in extraordinary fashion as the world No 1 squandered a seemingly unassailable lead and was beaten in five sets by Argentina’s Juan Manuel Cerundolo in the second round at Roland Garros.

Sinner, the top seed and pre-tournament favourite, led 6-3 6-2 5-1 and was serving for the match when his body suddenly betrayed him. Having controlled the contest with his usual clean baseline hitting and superior court coverage, he began to suffer severe cramping and complained of dizziness and nausea, a dramatic shift that turned the match on its head.

From 5-1 up in the third set, Sinner lost 15 consecutive points and called for a medical timeout mid-game as his movement visibly deteriorated. Cerundolo, ranked well below the Italian and making his main-draw breakthrough in Paris, seized on the opening with admirable composure, extending rallies and forcing Sinner to move as much as possible.

The Argentine reeled off six straight games to steal the third set 7-5, as Sinner’s serve speed dropped and his footwork became laboured. What had looked like a routine straight-sets victory for the top seed suddenly became a survival mission.

Any hopes of a swift recovery evaporated early in the fourth set. Sinner was broken twice, his legs buckling on wide balls and his forehand losing its usual penetration. Cerundolo, sensing history, continued to apply pressure without overhitting, cruising to a 6-1 fourth set and dragging the match into a decider that had seemed impossible an hour earlier.

The fifth set followed the same pattern. Sinner, clearly compromised, fought to shorten points but could not find the precision required. Cerundolo maintained his nerve, mixing heavy topspin with clever angles, and raced to another 6-1 set to complete one of the most remarkable comebacks in recent Grand Slam memory.

The result sends Cerundolo into the third round and leaves serious questions over Sinner’s physical condition and preparation, particularly given his status as the man to beat on tour. For the Italian, this will go down as a painful missed opportunity; for Cerundolo, it is a career-defining victory and a reminder that in best-of-five tennis, no lead is truly safe.