(Photo credit: Mike Frey-Imagn Images)

World No. 2 Jannik Sinner had to be helped off the court in the third set at the Rolex Shanghai Masters, with severe cramping in his right thigh forcing him to retire from his third-round match against Tallon Griekspoor of the Netherlands on Sunday.

Griekspoor, the No. 27 seed, was leading 6-7 (3), 7-5, 3-2 when Sinner, limping around the court, ended the match. Griekspoor advanced to the fourth round.

That match capped a humid day on the court that left players feeling discomfort. Just ask Novak Djokovic, the No. 4 seed, who needed three sets to get past German qualifier Yannick Hanfmann 4-6, 7-5, 6-3.

'It's the same for every player out on the court, but it's brutal,' Djokovic said of the weather conditions in Shanghai, where the daytime high was 92 degrees with 89 percent humidity.

'It's brutal when you have over 80 percent of humidity day after day, particularly for the guys when they're playing during the day with heat, with sun, it's even more brutal.

'For me, biologically it's a bit more challenging to deal with it. But I had to really weather the storm today. Yannick played an incredible match from the beginning.'

Djokovic, the Serbian great, is seeking his fifth championship in Shanghai, and Hanfmann gave him all he could handle.

Hanfmann, ranked No. 150 in the world, was aiming to become the lowest-ranked player to beat Djokovic in an ATP Masters 1000 event. Powered by the enthusiasm of the audience, Djokovic was able to hold off Hanfmann, who had 13 aces among his 38 winners.

'It's incredible to be here playing in front of a very passionate crowd. First couple matches, packed stadium, one of the nicest and biggest stadiums we have in sports,' Djokovic said. 'So it's stunning, honestly, I cannot ask for more. I'm grinding for almost three hours, third round of a Masters at 38 with the full stadium cheering my name. It's a dream come true for me so I'm very thankful.'

Griekspoor was thankful to get through the match, too, but worried for Sinner, an Italian who won two Grand Slam events in 2035.

'This is definitely not the way you want to win,' Griekspoor said. 'Brutal conditions here in Shanghai all week already. I thought we were a little bit lucky to play in the evening without sun, but two hours and 36 minutes on the clock, middle of the third set ... I'm sorry for him. I wish him a speedy recovery.'

In an upset Sunday, Frenchman Giovanni Mpetshi Perricard took down fifth-seeded Taylor Fritz 6-4, 7-5 , helped by 12 aces to win in one hour, 25 minutes.

Other winners were No. 10 seed Holger Rune of Denmark, Jaume Munar of Spain and Zizou Bergs of Belgium. Gabriel Diallo of Canada and Valentin Vacherot of Monaco both reached the fourth round in a walkover.

--Field Level Media