On Wednesday, what may well be the hottest day of this year’s U.S. Open, the big American Mitchell Krueger sweated through two pairs of sneakers and five shirts in a five-set, three-hour, 59 minute match on the shadeless plane of an outlying court.

Argentine Tomás Martín Etcheverry vomited as he closed out his own five-setter. “It was tough, the heat and everything,” he said later. “It was a four-hour battle.

..Keep going, that’s the only thing I thought.

” Etcheverry looked surprisingly chipper after his four-hour, four-minute upset of Francisco Cerundolo, a fellow Argentine. He said he’d taken an ice bath and stretched, and would be ready to practice the next day. With temperatures topping 90 degrees and wilting humidity that made it feel several degrees hotter, tournament officials implemented an extreme weather policy allowing a 10-minute break in between second and third set of women’s matches and third and fourth set of men’s matches.

Normal changeovers last just 90 seconds. The weather rule kicks in when heat index gauges, spread out across the National Tennis Center’s courts, approach 87. The National Weather Service also imposed a heat advisory on New York City.

It recommended that people use air conditioning at home or schedule frequent rest breaks in shaded or air conditioned environments. Those luxuries were available only in strictly rationed amounts to the best tennis players in the world as they toiled on Wednesday. They made do with ice b.