Dana Vollmer won a gold medal at the Olympics and set a world record to go along with it.

Vollmer got things going with a bang Sunday in the 100-meter butterfly. She was third at the turn but managed to power her way to the wall for a time of 55.98 seconds, beating the record of 56.06 set by Sweden's Sarah Sjostrom in a since-banned high-tech bodysuit at the 2009 world championships.

"I'm on top of the world right now." she said. "I still know I can go faster."

Vollmer, who made the Olympics as a 16-year-old in 2004, was slowed by injuries and health problems, making her question whether she even wanted to continue swimming.

Her injuries have since healed and during the U.S. Olympic trials last month, she came close to breaking Sjostorm's record.

Now she's an Olympic champion and now holds that record as her own.

"I kept telling myself that my strength is my second 50," Vollmer said. "I kept really calm."

Vollmer was the second swimmer to set a world record at the London Games, and only the fourth to break a mark set during the rubberized suit era. Those suits were banned after an astonishing 43 world records were set at the 2009 world championships.

Lu Ying gave China another medal at the Olympic Aquatics Centre, taking silver in 56.87. Australia's Alicia Coutts grabbed the bronze in 56.94.