Novak Djokovic is through to the third round of the US Open after a gruelling match came to a premature end when Laslo Djere was forced to retire with injury.

Defending champion Djokovic was leading 6-4 6-4 2-0 when an abdominal issue meant fellow Serb Djere was unable to continue.

Although the match went little more than two sets, the pair were on court for more than two hours in extreme heat and humidity in New York.

“It was a big fight, more than two hours for two sets,” Djokovic said.

“I served awful and without the serve, you have to grind, you have to run.”

The two scrapped for an hour in a ferociously contested first set before Djokovic found an extra gear to take it with a break to love.

Djokovic appeared to be struggling in the humid conditions early on and received treatment before the second set.

Djere sensed his chance, earned an early break and looked set to level the match at a set apiece, leading 4-2 and with two break points.

However, Djokovic held serve and, with his compatriot suddenly showing signs of discomfort, broke back in the next game.

A medical timeout did little to help Djere as Djokovic broke again to snatch the second set.

Despite being visibly in pain, Djere attempted to play on but when he failed to win a point in the first two games of the third set, he approached the net and retired.

That handed Djokovic his 90th win at Flushing Meadows, making him the only man to have won 90 matches at all four Grand Slams.

“It doesn’t get bigger than this in terms of a tennis stage,” the 37-year-old added.

“The atmosphere is incredible and it’s a great privilege to be able to play here again at my age.”

Djokovic will face 28th seed Alexei Popyrin of Australia in round three.​​​​​​​

Rublev comes back from brink

Image source: Getty Images

Image caption: Andrey Rublev has not gone beyond the quarter-finals of any of the four Grand Slams

Earlier, Andrey Rublev fought back from two sets down in brutally hot conditions to beat Arthur Rinderknech 4-6 5-7 6-1 6-2 6-2.

Sixth seed Rublev looked down and out at the end of the second set and was struggling physically and mentally in 33C heat.

However he persevered, only managing to lift his arms above his head in celebration after completing a draining win in four hours and six minutes.

Both Rublev and Rinderknech used ice packs and fans to try to cool down.

Rublev called for the doctor before serving for the match and could be heard telling them: “I’ve drunk too much, I’ve eaten too much,” adding he felt like he “had a baby” in his stomach.

The 26-year-old then stayed on court to sign autographs despite being visibly drained.

He will face 32nd seed Jiri Lehecka, who also came back from two sets down to beat qualifier Mitchell Krueger, next.

Fourth seed Alexander Zverev continued his search for a first Grand Slam title with a 6-4 7-6 (7-5) 6-1 victory over Alexandre Muller.

The 27-year-old reached the final in New York in 2020 as well as the French Open final earlier this year.

However, he lost the US Open showpiece to Dominic Thiem from two sets up and led Carlos Alcaraz by two sets to one in Paris before succumbing to the Spaniard.

Zverev said he had doubts he could return to the top level after sustaining a serious ankle injury at the French Open in 2022.

The fourth seed has won 54 singles matches this year – more than any other male player on the tour.

“I had so many doubts, question marks whether I would ever be top 10 or top five in the world [again],” Zverev said.

“It was something that was taken away from me two-and-a-half-years ago and I’m extremely glad to be playing at this level. ”

Zverev will face Argentina’s Tomas Martin Etcheverry next.

Home home Frances Tiafoe was leading Alexander Shevchenko 6-4 6-1 1-0 when the Kazakh retired with injury, while ninth seed Grigor Dimitrov brushed aside Australia’s Rinky Hijikata 6-1 6-1 7-6 (7-4).

In the evening session, Norwegian eighth seed Casper Ruud overcame France’s Gael Monfils 6-4 6-2 2-6 7-6 (7-3).

American Taylor Fritz, the 12th seed, is also through after a comfortable 6-3 7-6 (7-1) 6-1 victory over Matteo Berrettini of Italy.

It was less comfortable for Berrettini’s compatriot Lorenzo Musetti as he beat Serbia’s Miomir Kecmanovic in a five-set thriller.

Musetti saved two match points before clinching a 3-6 6-4 6-4 2-6 7-5 win in three hours and 47 minutes.

He celebrated by taking his shirt off and letting out a loud scream as the crowd chanted his name.