There was to be no relief on Tuesday, with heat advisory issued by National Weather Service thanks to expected temperatures of around 34 C
Sloane Stephens dumped out of US Open even as other contenders feeling the heat
Sloane Stephens's US Open title defence ended with a 6-2, 6-3 quarter-final defeat to Anastasija Sevastova on Tuesday as the Latvian avenged a 2017 loss to the American at the same stage.
Sevastova, through to the semi-finals of a grand slam tournament for the first time, will face either 23-time major champion Serena Williams or eighth-seeded Czech Karolina Pliskova for a place in the final after toppling Stephens in brutal heat and humidity on Arthur Ashe Stadium.
"I think it was very physical today. It’s tough to play, so hot in here. The first set was so important," said the 19th-seeded Sevastova, who broke Stephens in the final game to pocket the opening set.
She earned the last of five breaks in the second set to take a 5-3 lead and served it out on her third match point when a weary Stephens put a backhand into the net.
"I showed some nerves at the end but it’s normal," Sevastova said.
With the heat, humidity and blazing sun combining to make conditions hazardous enough that organisers suspended junior matches, the scraps of shade on the massive Ashe court were invaluable.
"When the shade was there it was so hot here and amazing there," Sevastova said of the contrast of playing on the shady or sunny end of the court.
"The last games, it was good that I played in the shade. The sun was not comfortable and it was hot."
Stephens was ranked 83rd in the world when she upset Sevastova in three sets in the quarter-finals last year, trailing by a break in the third set before winning it in a tiebreaker.
Now No 3 in the world, Stephens joined an exodus of women's seeds that saw top-ranked Simona Halep and No 2 Caroline Wozniacki exit in the first two rounds.
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Staying on the topic of heat, there was to be no relief on Tuesday, with a heat advisory issued by the National Weather Service thanks to expected temperatures of around 34 C and humidity of 60 per cent.
Roger Federer said after his defeat to to John Millman in the fourth round that he thought such conditions had become more problematic on Ashe since the addition of the retractable roof led to diminished airflow in the 23,000-seat stadium.
But players have suffered on all courts - five retiring from heat-related problems in the first round to prompt organisers to implement an extreme heat policy allowing a 10-minute break in both men's and women's matches that go beyond straight sets.
It is the first time in grand slam history that such a break has been offered to the men.
The break proved less useful in Week 1 to players toiling on outside courts - far away from the sanctuary of a locker room.
They were to continue to monitor the measurement and resume play when it dropped below 32.2 C.