Katie Ledecky sealed her fourth gold medal in Rio on Friday night, winning the 800-meter freestyle in her second straight Olympic Games and posting a new world record.
Her time of 8:04.79 broke her own world record mark of 8:06.68, in her final race of the Rio Games.
Ledecky entered as the runaway favorite and world record-holder in the event. She narrowly missed setting the world record in London in 2012.
On Thursday, Ledecky set an Olympic record with a time of 8:12.86 in her preliminary heat. In that race, she was seven seconds ahead of the next competitor. She now owns the 13 fastest times ever posted in the event.
Ledecky becomes the first Olympic swimmer to sweep the 200-, 400- and 800-meter freestyle events since the 1968 Mexico City Games, and the second woman to accomplish the feat.
She has now won five medals (four golds and one silver) in Rio, racing as the youngest member of the U.S. swim team. Including the 2012 gold, she has amassed five Olympic wins at age 19.