You listened to the tennis players at the U.S. Open talking shop amongst themselves today, and the conversation centered less around who is sharpest than who is fittest. They were not talking about who is most likely to succeed, but rather who is least likely to melt like a scoop of Swensen's sticky, chewy chocolate.

Then you wandered around the asphalt-based hard courts of the National Tennis Center, where the air this week has been like a polluted steambath, and you could see why. The smell of sweat was everywhere. Players slogged through matches, perspiration pouring out of them until their clothes clung to them like a clammy second skin. Complexions reddened like ripening strawberries and hair matted itself into porcupine coiffures.

At change games, players wearily slumped into their chairs and slugged water, soft drinks or Gatorade as if trying to extinguish fires in their bellies. They gulped salt pills and mineral tablets, poured tennis cans full of water over their heads and buried themselves under set towels. Men changed their shirts. Undoubtedly some considered emulating Ilie Nastase and changing their shorts. Players of both sexes changed out of squishy socks.

It was 90 degrees this afternoon at Flushing Meadow Park. The relative humidity was 90 percent. The Air Quality Index must have been frightening, judging from that most reliable gauge: the congested lung. The atmosphere seemed as hot and sticky as the top of a pizza, and what breeze there was amounted only to a breath of stale air.

Dozens of spectators were treated for heat prostration in the first-aid room underneath Louis Armstrong Stadium. Players in anything less than top shape -- especially the men, who are playing best-of-five-sets from the first round of Open for the first time since 1974 -- were suffering. Five first-round matches ended in defaults, and many more in tame, exhausted surrenders. Californian Bob Lutz got dizzy. Betty Stove got sick to her stomach. Both had to quit.

"The weather? There are only three words for it: 'Hot as hell,'" said Brian Gottfried, who looked surprisingly fresh after running Van Winitsky off the broiling stadium court, 6-4, 6-2, 6-2.

Gottfried, 27, grew up in Florida. A tireless worker, he thinks nothing of practicing six or eight hours a day in the sun. He is used to it. But even for him, Flushing Meadows in August is an ordeal.

"You can't breathe here. It's hotter in Florida, but there you're happy to be outside. The sun's shining, the air's clean, you sweat and feel good," he said. "Here you need an oxygen mask and maybe a pair of galoshes. You die."