LONDON -- Dana Vollmer put her hand to mouth once she cleared her goggles.
The Cal graduate knew she had the gold medal. Soon she realized she also had a piece of history.
After failing to make the Olympic team in four events four years ago, Vollmer became the first woman to break the 56-second barrier in the 100-meter butterfly, winning her signature event Sunday night at the Aquatics Centre in 55.98 seconds.
Relying on a smooth and powerful second half of the race, Vollmer, 24, annihilated the field, with China's Ying Lu finishing second in 56.87 and Australia's Alicia Coutts taking third in 56.94.
Coutts gave Vollmer a long embrace in the pool afterward.
"Obviously it's great to be part of such an historic occasion, and Dana's such a beautiful person; she really deserves it," Coutts said.
Few could question that on a night the French earned revenge in the men's 400 freestyle relay when Yannick Agnel surged past American Ryan Lochte on the anchor leg to seize the gold medal. It came four years after American Jason Lezak chased down the French anchor to preserve Michael Phelps' historic gold-medal run in Beijing.
It was another big night for American swimmers as veteran Brendan Hansen grabbed a bronze medal swimming from the eighth lane in the men's 100 breaststroke, and Allison Schmitt broke a U.S. record in earning a silver medal in the 400 freestyle.
But Vollmer has had the most dramatic turnaround among American swimmers. Four years ago at the U.S. trials, she finished fifth in the 100 butterfly and seventh in the 200 freestyle, and she didn't even make the finals of the 50 and 100 freestyle events.
Devastated and dispirited, Vollmer considered walking away from the sport she loved. She was physically hurting from back and shoulder injuries and an unknown stomach illness.
"I was tired of being sick all the time," Vollmer said.
But Cal coach Teri McKeever -- the U.S. Olympic coach -- gently guided the swimmer back to life. Together they worked on getting healthy. With back and shoulder injuries conquered, Vollmer solved a stomach problem by changing her diet to gluten-free foods.
"I just finally get to train and push myself without fear of hurting," Vollmer said. "To keep going with that and ride that, I couldn't have imagined that in 2008."
Vollmer, who is among the postgraduate swimmers who train with McKeever in Berkeley, took eight-hundredths of a second off the world record set in 2009 by Sweden's Sarah Sjostrom, who was fourth Sunday. She also took 0.63 off the Olympic record set by Holland's Inge de Bruijn at the 2000 Sydney Games.
Vollmer didn't have the fast start she enjoyed in the semifinals Saturday. But she didn't want to do that again, saying it took too much energy.
"I kept telling myself my strength is my second 50," Vollmer said. "Normally I am not in the lead after my start, so I just set it up well and was passing people and charging my way home."
New Zealander Lauren Boyle watched her former Cal teammate intently on a screen before her own 400 freestyle final.
"It was so inspiring," she said of Vollmer's race.
Vollmer, from Granbury, Texas, has been a huge inspiration throughout her career. She overcame two heart defects as a teenager to qualify for the 2004 Olympic team and win a relay gold medal.
Vollmer attended Florida before transferring to Cal. She has never looked back since landing in Berkeley, where McKeever's unorthodox coaching techniques helped allow Natalie Coughlin to blossom into one of history's greatest swimmers.
Vollmer credited McKeever and her Australian stroke coach Milt Nelms for her transformation. Vollmer, like Coughlin, has spent time in Australia training in the ocean.
Swimming against forceful waves left her confident and feeling relaxed while gazing at the pool just before the starting gun Sunday.
The pool looked "calm and flat and full of potential," Vollmer said.
It also was full of golden dreams as the swimmer left all comers in her considerable wake.