Second day of stifling heat and humidity at the US Open prompts tournament organisers to implement special rules to provide relief for suffering players.
Roger Federer made light of energy-sapping conditions to brush past Japan's Yoshihito Nishioka 6-2, 6-2, 6-4 in his opening match at the US Open on Tuesday.
Where other players had slogged through long rallies as the temperature hit 90 Fahrenheit (32C), Federer kept his time on court to a minimum with a masterclass of serve-and-volley tennis, pulling the industrious world number 177 from one side of the court to the other at will.
Federer, the second seed, broke the Japanese left-hander in the opening game of the one-sided encounter and never looked back, rattling through his service games with a minimum of fuss to wrap up the first set in 28 minutes.
The Swiss took 35 minutes to close out the second and, with Nishioka firmly on the ropes, started the third by racing to a 4-0 lead before his Japanese opponent held serve.
Nishioka rallied briefly at the end, denying Federer the chance to serve out the set and battling back to 5-4 with his first break of serve.
But Federer put his beleaguered opponent out of his misery in his next service game, wrapping up the victory in one hour and 52 minutes.
Next up for the Swiss is a second-round clash with unseeded Frenchman Benoit Paire.
Earlier, Novak Djokovic overcame Hungary's Marton Fucsovics 6-3, 3-6, 6-4, 6-0 in punishing temperatures that prompted officials to observe a heat rule for men's singles matches for the first time.
The players took a 10-minute break between the third and fourth sets to help them cope with temperatures climbing above 90 degrees Fahrenheit (30 degrees Celsius).
The pair, who were not allowed to speak to their coaches during the break, spent the downtime side-by-side, "naked in the ice baths", Djokovic said in a post-match broadcast interview.
"It was quite a magnificent feeling, I must say," he added.
After claiming the first set, a visibly exhausted Djokovic smashed his racket as Fucsovics led 3-2 in the second.
In between the action, both players draped themselves in ice towels and at one point Djokovic sat shirtless in his seat.
"I was obviously hoping and praying that I'll get to feel better as the match progresses," Djokovic told reporters after the match.
"Obviously I felt better, especially after that 10-minute break. For the first three sets, it was a survival mode for both of us."
The Serb came roaring back in the third set, clawing his way from 3-1 down before sweeping Fucsovics in the fourth.
"I had to find a way to dig myself out of the trouble," Djokovic said.
"I think that was a turning point. 4-3 in the third when he was serving, I managed to play a good game."
Djokovic was back at the US Open for the first time since 2016 after claiming his fourth Wimbledon title this year and completing a sweep of Masters series events.
Zverev eases past lucky loser Polansky
Fourth seed Alexander Zverev hardly broke sweat despite the sweltering US Open heat. The German dispatched Canadian lucky loser Peter Polansky 6-2, 6-1, 6-2 in a first-round match that lasted just over an hour and a half.
The 21-year-old won 83 percent of his first serves, fired 10 aces and never faced a break point as he cruised past Polansky and set up a second-round showdown with Nicolas Mahut of France.
"I played well from start to finish," Zverev said in an on-court interview. "It's never easy and obviously the conditions are tough for everyone because of the heat and humidity.
"Tennis is very tough sport."
The loss ends a remarkable run for Polansky who this year became the first player ever to qualify for all four Grand Slam tournaments as a lucky loser, although he fell in the first round of all of them.
The lucky loser is a player who has lost during qualifiers but makes the main draw because of a withdrawal and has his name picked at random.
Zverev's win was his first at a major under the tutelage of former world number one Ivan Lendl.
"Thanks to him for joining my team," said Zverev, who many pundits believe has the best chance of any of the young crop of men's players to make a deep run at the tournament.
"Hopefully this match is the beginning for us."
Kerber banishes US Open hangover with first round win
Fourth seed Angelique Kerber showed that she has fully recovered from last year's US Open hangover by disposing of Russian Margarita Gasparyan 7-6(5), 6-3 to reach the second round at Flushing Meadows.
Champion in 2016, Kerber's title defence ended almost before it began 12 months ago with the German suffering a 6-3, 6-1 first round shellacking by Japan's 46th ranked Naomi Osaka.
That upset provided a sobering reminder that anything can happen at a grand slam and Kerber made sure she would not be caught with her guard down again this year as she took on a player making her US Open main draw debut.
A three-time Grand Slam winner against an opponent sitting at 370 in the world rankings and making her first appearance in a major in more than two years would appear a mismatch but it was a contest Kerber approached in a business-like manner.
Despite the background Gasparyan, who has a WTA Tour title on her resume, represented a potentially tricky first round opponent, returning to the circuit this season after missing 15 months recovering from a career-threatening knee injury.
"This is the first time that we played against each other, and she was really hitting the balls really good, really clean," said Kerber. "I knew that she was injured for a long time... Now she's coming back.
"If she's playing like this in the next weeks and months, for sure, she (will) soon (be) really high in the rankings."
The Russian showed some of her potential and a fair amount of grit by battling to take Kerber to a first set tiebreak but the Wimbledon champion kept her cool on a sweltering day on Louis Armstrong Stadium court to prevail 7-5.
The 23-year-old Gasparyan refused to wave the white flag and broke Kerber to open the second set, but the German broke back immediately to slowly seize control and wrap up the match.
"It was really not easy out there today," said Kerber. "I think it's one of the hottest days that I remember here.
"But at the end, when you're out there, you just try to survive a little bit."
Wozniacki breezes past sloppy Stosur
Former world number one Caroline Wozniacki cruised past error-prone Samantha Stosur 6-3, 6-2 to reach the second round.
The Dane, who is the highest seed left in the draw after top seed Simona Halep fell in the first round on Monday, needed less than 90 minutes to get past the Australian, who committed 34 unforced errors and eight double faults.
The quick and comfortable win was a relief for the 28-year-old Wozniacki, who was able to get out of the blistering New York heat in relatively short order and save energy for her second-round match against Ukrainian Lesia Tsurenko.
"I'm just thinking I'm on the beach with a margarita in my hand," Wozniacki said when asked about coping with the heat during an on-court interview.
The second seed showed no sign of the knee injury that forced her to retire midway through her match against Kiki Bertens at the Cincinnati Open earlier this month, moving well throughout the match.
The veteran Stosur, the tournament's 2011 champion, briefly looked like she might deliver a second big upset in the women's draw when she broke Wozniacki early in the first set but the Dane broke right back to take a 4-3 lead she did not relinquish.
The second set was more straightforward as Stosur struggled to control her forehand on a hot day that sent balls flying and overheated fans into the shady sections of Arthur Ashe Stadium.
Twice US Open finalist and New York resident Wozniacki advanced when Stosur double faulted on match point.
"I'm happy that I got through this one," she said. "I'm going to celebrate the win today and tomorrow think about the next one."
Cilic reaches second round after Copil retires hurt
Marin Cilic clinched a second-round berth at the US Open after opponent Marius Copil of Romania retired hurt in the third set trailing the seventh-ranked Croat 7-5, 6-1, 1-1.
Cilic, who was champion in 2014, was cruising against Copil, who quit with a left-arm strain, according to a USTA official.
The match took place in heat and humidity, as temperatures climbed above 90 degrees Fahrenheit (30 degrees Celsius), battering players across Flushing Meadows.
Seventh seed Cilic, who said it was "one of the most brutal days that we had so far this year," told reporters the heat, plus the pressure of the shot clock introduced at the tournament this year, had proved challenging.
"I was just missing some easy balls, making some unforced errors that are not that usual for me," Cilic said, referring to his performance early in the match. "Conditions definitely were extremely tough and very humid, very hot."
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