NEW YORK — His cheeks red, hair matted with sweat, Novak Djokovic appeared to be in such distress as he trudged to a changeover on a steamy U.S. Open afternoon that someone suggested it would be a good idea to have a trash can at the ready, just in case he lost his lunch.

Djokovic sat down and removed his shirt. He guzzled water from a plastic bottle. He placed one cold towel around his neck, a second across his lap and a third between his bare upper back and the seat.

He was not even 11/2 hours into his first match at Flushing Meadows in two years, and while Djokovic eventually would get past Marton Fucsovics 6-3, 3-6, 6-4, 6-0 Tuesday, it was a bit of an ordeal.

“Survival mode,” Djokovic called it.

With the temperature topping 95 degrees and the humidity approaching 50 percent – and that combination making it feel more like 105 – nearly everything became a struggle for every player across the grounds on Day 2 of the U.S. Open, so much so that six quit their matches, with three citing cramps or heat exhaustion.

About 2 hours into the day’s schedule, the U.S. Tennis Association decided to do something it never had at this tournament: offer men the chance to take a 10-minute break before the fourth set if a match went that far. That is similar to the existing rule for women, which allows for 10 minutes of rest before a third set when there is excessive heat.

The whole thing raised several questions: Should the genders have the same rules moving forward? Should the U.S. Open avoid having matches during the hottest part of the day, not just for the players’ sake but also to help spectators? Should the men play best-of-three-set matches at majors, instead of best-of-five? Should the 25-second serve clock, making its Grand Slam debut here, be shut off to let players have more time to recover between points?

“At the end of the day, the ATP or a lot of the supervisors, they’re kind of sitting in their offices, where (there’s) an A.C. system on, where it’s cool. And we have to be out there. They tell us it’s fine; they’re not the ones playing,” said No. 4 seed Alexander Zverev, who won in straight sets in the early evening, when it was far less harsh. “For sure, the rule should be more strict.”

How bad was it out there at its worst?

“Bloody hot,” said two-time major semifinalist Johanna Konta, who lost 6-2, 6-2 to No. 6 Caroline Garcia.

“Brutal,” said 2014 U.S. Open champion Marin Cilic, who advanced when his opponent retired in the third set.

“Really not easy,” said three-time Grand Slam title winner Angelique Kerber, who defeated Margarita Gasparyan 7-6 (5), 6-3.

“Terrible. It’s awful out there,” said Tennys Sandgren, an American who won in straight sets and will face Djokovic in the second round. “I don’t know how guys are hanging in there. I was thinking in the third set, like, ‘It’s getting really bad. I just don’t know how long I have to play out there.’ And I think everybody kind of feels similarly.”

Djokovic certainly did.

“Everything is boiling – in your body, the brain, everything,” said Djokovic.

In an evening match, Roger Federer improved to 18-0 in first-round matches by beating 117th-ranked Yoshihito Nishioka, 6-2, 6-2, 6-4.