Beginning an audacious week, Katie Ledecky claimed two gold medals on the opening night of swimming at the world championships Sunday.

The 20-year-old American pulled away for a dominating win in the women's 400-meter freestyle, though she failed to break her own world record. She finished more than 3 seconds ahead of the runner-up, teammate Leah Smith. China's China's Li Bingjie claimed the bronze.

Ledecky returned to the pool about an hour later for the 4x100 free relay, putting the U.S. ahead to stay on the third leg.

Sarah Sjostrom set a blistering early pace for Sweden, and Ledecky actually slipped to third on the flip after her first 50. But she had powered to the front by the time she passed off to Olympic champion Simone Manuel, who closed it out for the Americans.

Australia took the silver, while the bronze went to the Netherlands.