Andrey Rublev fought back from two sets down in brutally hot conditions to beat Arthur Rinderknech and reach the US Open third round.

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 a draining 4-6 5-7 6-1 6-2 6-2 win in four hours and six minutes.

A heat warning is in place in New York, with both Rublev and Rinderknech using 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 the 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 was among the early winners on day three in New York, with Novak Djokovic featuring in the night session later on Wednesday.

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.

"What changed is I'm enjoying every single moment on these beautiful courts in front of thousands of fans.

"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.

"Hopefully I can give myself the best chance to win here."

Zverev will face Argentina's Tomas Martin Etcheverry next.

American Frances Tiafoe and ninth seed Grigor Dimitrov were also among the winners on the third day in New York.

Home favourite Tiafoe was leading Alexander Shevchenko 6-4 6-1 1-0 when the Kazakh retired with injury, while Dimitrov brushed aside Australia's Rinky Hijikata 6-1 6-1 7-6 (7-4).

Defending champion Novak Djokovic features in the night session on Arthur Ashe, with Andrey Rublev and Taylor Fritz also in action.