ATHENS, Greece - It wasn’t even noon Thursday, and already they were getting half-naked at the pool.

As some of the best swimmers in the world raced through the 100-meter butterfly, the stands were filled with shirtless men and bikini-clad women. People covered their heads with towels, flags, bandanas — anything that would ward off the broiling rays. The stairwells were filled with fans desperate for a patch of shade.

Temperatures soared into the mid-90s, and the Olympic flame paled in comparison to the scorching sun.

“I’m about ready to dive into the pool on top of one of the swimmers,” said 22-year-old Amy Tzagournis of Columbus, Ohio, who had stripped down to short-shorts and a bikini top. “I’m pretending I’m at the beach.”

The high temperatures were more than an annoyance in some sports. Athletes worried their performances would wither. Coaches broke out cooling vests, ice wraps — even “ice chairs,” where tennis players and other athletes can dunk their arms in freezing water.

“The environment issues are a big deal in these Olympics, more so than in the past, with high heat, pollution and reflective surfaces,” said Dr. David Weinstein, head physician for the U.S. Olympic team.

“It’s illness and injuries, but also performance,” he said. “Even a small amount of body-weight loss — 2 or 3 percent — can lead to a significant deterioration in the muscle strength and power, as well as endurance capacity.”

On the Olympics’ first day, when the dry heat reached 104 degrees, cycling officials changed a rule, letting team cars hand water bottles to riders. Weary cyclists slid ice packs down their jerseys, and about half the men’s field was unable to complete the 139-mile race.

Slide show   Visions of gold: Aug. 29 Demark throws for handball gold, Argentina takes it to the net and Britain's Mark Lewis-Francis jumps for joy.

At the beach volleyball stadium Thursday, Brazilian star Adriana Behar complained during a match with Cuba that the sizzling sand was burning her bare feet. But when Behar asked the Greek referee to hose down the sand for relief, she coolly replied: “No.”

“It was hot, very hot,” said Behar, who was able to gut out a victory with partner Shelda Bede.

Still, the hottest venue was probably the pool — and not just because of the swimmers. Organizers planned to put a roof on the aquatic center, but the idea was canceled because of soaring costs and the rush to get ready for the games.

Swimmers said the lack of a roof didn’t matter much, but it was a different story for the fans.

“By the end of the day it’s almost too hot to eat,” said Bronwen Burmester of Tauranga, New Zealand. “We drank four bottles of water in one hour. Our lipscreens have melted.”

She and her husband, Greg, draped kiwi sports flags over their heads, but said sometimes they almost wished they were rooting for someone else.

“New Zealand has black flags. We want to wear black clothes, but it’s too hot,” she said. “You’re lucky if you have a light-colored country.”

The swimming events are the worst because the stands are almost entirely in the sun, and the water reflects its rays right back up at fans.

“Water, water, water, water,” was the mantra for Gerda Gesman of Rijnsaterwoude in the Netherlands, holding a battery-powered fan to her bright-red face. “We like to sit in the shade, but here there is no shade.”

Minutes later, she had abandoned her seat for a breather in the shaded stairwell. Hundreds of others had the same idea.

“It’s like a sauna,” said Josephine Joergensen of Aarhus, Denmark, gasping for air by the refreshment stand. “It’s too hot out there.”

Journalists covering the meets were suffering as well, with some wearing hoods and gloves against the sun. A few burned their hands when they touched their computer mice; the lenses on one reporter’s sunglasses melted in the sun’s blazing rays.

Olympics officials have dotted venues with drinking fountains, and announcers remind fans to drink water and use sunscreen. First-aid tents have nurses to help anyone with heat exhaustion or sunstroke. But officials said they’ve logged only 17 heat-related cases so far, accounting for 0.034 percent of those seeking help.

Coaches lectured athletes on staying hydrated and covering up. A sign at the apartments where the U.S. softball team is staying was printed on a bright yellow sheet: “If your urine in the color of this paper, you are not drinking enough.”

Athens is hot, but major sports events have been held in worse heat. Temperatures climbed into the 100s at the 1996 Atlanta Games, where it was much more humid than in Athens. Sydney, though, was cool at the 2000 Games because winter was just ending in the southern hemisphere.

At last year’s Pan-American Games in the Dominican Republic, officials dropped large blocks of ice into the swimming pool after the Canadian team complained the water was intolerably hot. A field hockey match between the United States and Chile was delayed for an hour while players waited for fire trucks to hose down the parched field.

So far in Athens, most athletes said they have been able to manage.

“The sun hits you in the face when you’re swimming the backstroke, but with a good pair of goggles there isn’t a problem,” Uruguayan swimmer Serrana Fernandez said. “I like it being open, because I suffer a lot when it’s cold.”