This piece originally appeared on SI.com.
American swimmer Katie Ledecky took home gold in the 400-meter freestyle on Sunday night, and shattered her own world record in the process.
The 19-year-old finished her four laps in 3:56:46, topping her then-record time of 3:58:37 at the 2014 Pan Pacific Championships by nearly two seconds.
Ledecky already had a silver medal to her name, placing second in Saturday’s 4×100-meter freestyle relay. She will race again on Monday afternoon in the 200-meter freestyle heats, and in the heats for the 800-meter free on Thursday.
The gold is the first for the United States this year in swimming.