What began as a slow day for China's favored swimmers ended as a big night for underdogs.
Le Jingyi salvaged the first day of competition for the Chinese, winning the 100-meter freestyle in an Olympic record time in the opening event.
But the United States had two medals, a silver and a bronze, to celebrate.
Allison Wagner of Gainesville won the silver in the 400 individual medley. Her loss was Ireland's gain, as Michelle Smith gave her country its first swimming gold.
Following the excitement of her achievement, Smith, a three-time Olympian from Dublin mouthed the words to the Irish national anthem during the awards ceremony.
Smith did all right for being Ireland's only world-class female swimmer.
She led after 100 meters of butterfly and 50 of backstroke, then dropped to third behind Krisztina Egerszegi of Hungary and Wagner. Smith regained the lead coming home in the freestyle, winning in 4:07.98.
"I'm still in shock," Smith said. "I can't do much better than that."
Wagner, who was 18 for the race but turns 19 today, finished at 4:09.30.
"I expected to swim fast," she said. "I gave it all my effort. I can't ask any more of myself."
Angel Martino of Americus, Ga., the oldest U.S. Olympic swimmer in 72 years, won bronze in the 100 freestyle as hometown fans cheered her on. She waved as she received her medal and, a few minutes later, handed it to a friend suffering from cancer.
"I'm happy to do it here at a big meet," Martino said of her medal. "I'm sorry it wasn't a gold. I gave it everything I had. I just didn't have enough left at the end."
Le added an Olympic record to her world mark in the 100-meter freestyle by winning in 54.50 seconds after Martino led at the 50-meter mark.
Sandra Volker of Germany got the silver medal in 54.88, and Martino finished in 54.93. The other American, Amy Van Dyken, came in fourth in a career-best 55.11 but needed assistance from trainers on the pool deck after the race. She was reported to be suffering from tingling in her back and cramps in her legs. She and Martino are scheduled to swim the 4x100 freestyle relay tonight.
After leaving the pool, Le smiled and waved to the crowd in a rare moment of triumph for her country. China's program, bedecked with gold medals but blemished by steroid use, sustained a surprising blow when three of its five swimmers competing Saturday morning missed qualifying for the finals.
Le's world record is 54:01, and the Olympic best was 54.51 by her countrywoman, Zhuang Yong, at the 1992 Olympics.
At the Rome World Championships, the Chinese won gold medals in 12 of 16 women's events. Two weeks later seven of their swimmers, including two world champions, tested positive and were suspended for two years.
The medal was another milestone in Martino's comeback from her ban from the 1988 Olympics for using a substance that she claimed came from birth control pills. In 1992, she won two golds and one bronze at Barcelona.
She is 29, the oldest U.S. female swimming Olympian since Frances Schroth was a swimming alternate in 1924.
China was banned from the Pan Pacific Swimming Championships in August, held in the same Georgia Tech pool as the Olympics.
That absence and a lack of information coming out of that country kept Americans in the dark about just how strong the Chinese were.
China's slide from prominence was most evident in the 400 IM. Chen Yan had the 17th best time and Wu Yanyan the 18th, both swimming about 13 seconds slower than they did at their national trials in April.
Shan Ying, whose 54.40 is the third-fastest 100 freestyle time in history, also missed the final as the ninth fastest qualifier in 56.10. And Zeng Qiliang barely made it, finishing eighth in the men's 100 breaststroke heats.
Fight to the finish
In a tight race in the women's 100-meter freestyle, China's Le Jingyi touches just ahead of Sandra Volker and Angel Martino, winning in an Olympic record time of 54.50 seconds.
Lane 1: Mette Jacobsen, 56.01
Lane 2: Karin Brienesse, 56.12
Lane 3: Sandra Volker, 54.88
Lane 4: Le Jingyi, 54.50
Lane 5: Angel Martino, 54.93
Lane 6: Franzi van Almsick, 55. 59
Lane 7: Amy Van Dyken, 55.11
Lane 8: Sarah Ryan, 55.85