Jannik Sinner was helped from the court on Sunday after withdrawing from his third-round match at the Shanghai Masters due to what appeared to be severe cramp.
The world No 2, who won the title in Beijing last week, was locked in a three-set battle with Dutch player Tallon Griekspoor in humid conditions, but was forced to pull out of the contest after two hours and 35 minutes.
Sinner’s issues started at the end of the second set, which he lost 7-5, before the fifth game of the third set saw the Italian struggle immensely, barely able to serve and move around the court.
Sinner, 24, could barely walk by the end of the game and required assistance getting to his bench from a trainer courtside.
Despite a leg massage, the defending champion was unable to continue and limped off-court, again with the aid of a trainer.
Sinner’s withdrawal from the penultimate Masters 1000 event of the year comes at a tournament which arch-rival Carlos Alcaraz opted not to play, as the Spaniard focused on rest and recovery after his title win in Tokyo.
Sinner’s participation in the Saudi Arabian exhibition tournament, the Six Kings Slam, is now in doubt. The event starts on Wednesday, 15 October.
It is also unclear at this stage whether Sinner will undertake his usual post-match media duties in Shanghai.
Yet Griekspoor, the 27th seed in Shanghai, progresses to the fourth round where he will play Monegasque qualifier Valentin Vacherot.
Novak Djokovic, meanwhile, came through a three-set battle against Yannik Hanfmann to reach the fourth round.
“The crowd got me up, and towards the end of the second set I started to get into it more,” said the world number five after a 4-6 7-5 6-3 triumph.
“I have often had to fight in matches that maybe I wasn’t the better player – battling through is something I am quite familiar with throughout my career.
“But I hung in there and showed a lot of guts.”