New York: Simona Halep and Stan Wawrinka beat the heat with straight-sets wins to reach the third round of a sweltering U.S. Open on Thursday while American hope Jack Sock wilted under the punishing conditions, collapsing on court.
However, Andy Murray and Johanna Konta showed British players can sweat it out for a win as both went the distance to claim second round victories.
Third seed Murray came out ice cold on a broiling afternoon but caught fire and rallied for a five-set 5-7 4-6 6-1 6-3 6-1 win over Frenchman Adrian Mannarino.
Konta, meanwhile, provided the upset of the day after toiling for three hours and 27 minutes under a blazing sun to see off ninth-seeded Spaniard and Wimbledon finalist Garbine Muguruza 7-6(4) 6-7(4) 6-2.
"We need to believe, which is not always easy," Murray told reporters. "Obviously, I had quite a few opportunities, I think I was one for seven on breakpoints (in the first set).
"I just wasn`t able to break at any of the important moments, unfortunately. I just had to kind of tell myself that I would get there eventually. Managed to turn it round."
As courtside temperatures pushed past 100 degrees Fahrenheit (38 degrees Celsius) at Arthur Ashe Stadium, Romanian second seed Halep wasted little time finishing off Ukraine qualifier Kateryna Bondarenko 6-3 6-4 in just 76 minutes before escaping to the air-conditioned comfort of the players` lounge.
Fifth-seeded Swiss Wawrinka outslugged promising South Korean teenager Chung Hyeon, but still needed three tiebreaks to sweat out a 7-6(2) 7-6(4) 7-6(6) second round decision.
"Today was a really tough day with the conditions," Wawrinka said. "You have to really be careful how you get ready for the match, what you eat, what you`re going do and what you`re going take during the match.
"I know that I`m ready physically to battle for long hours in that condition. Today was hot, was humid, but still we play three hours and I`m feeling OK."
Next up for the French Open champion is Ruben Bemelmans of Belgium, who advanced when Sock retired due to cramping while leading 6-4 6-4 3-6 1-2.
Sock had looked in control of the match but began to show signs of distress in the third set, then sent shockwaves through the crowd when he began to cramp and dropped to the court as medical staff rushed to his aid.
The American grimaced in pain as he was wrapped in chilled towels with bags of ice also placed around his body.
A wheelchair was brought out but after several minutes, Sock was helped to his feet and, assisted by a trainer under each arm, limped off the court.
The week-long heatwave has taken a heavy toll at the year`s final grand slam with 12 players retiring due to the conditions or because of injuries in the opening round before Sock added his name to the casualty list in the second.
There was more upbeat news for American fans, however, as 13th seed John Isner blasted his way into the third round, pounding 17 aces in a 6-3 6-4 6-3 win over Russia`s Michael Youzhny, while Donald Young claimed his second-round match with a 3-6 6-4 6-4 6-2 decision over Britain`s Aljaz Bedene.
Germany`s Angelique Kerber, the 11th seed, also took the express route into the third round by taming Italian Karin Knapp 7-5 6-2, while 20th seed Victoria Azarenka of Belarus was a 7-5 6-4 winner over Belgium`s Yanina Wickmayer.
Australian Sam Stosur, the 2011 U.S. Open champion and last player to beat world number one Serena Williams at Flushing Meadows four years ago, looked ready to make another run at the title as she crushed Russian qualifier Evgeniya Rodina 6-1 6-1.