Superstar Olympic swimmer Katie Ledecky has just managed to overcome her greatest adversary yet -- herself. In a remarkable performance on Sunday night, Ledecky completely destroyed the world record for the 400-meter-freestyle event, earning a much-deserved gold medal in the 2016 Rio Olympics.

Now 19 years old, Ledecky seems to be a far cry from her 17-year-old self, completely dominating the event and finishing almost five seconds before the silver medalist, Britain's Jazz Carlin. U.S. teammate Leah Smith took the bronze medal.

With her performance on Sunday, Ledecky has now set the bar very high for the 400-meter freestyle, with a very impressive time of 3:35.46. Back when she was 17, she already broke the 4-minute barrier, setting the record at 3:58.37.

American athletes who join swimming competitions in the Olympics usually have to contend with the notion that they are competing under the shadow of Michael Phelps, arguably the most accomplished Olympian from the United States. Regardless of this, though, many believed that Ledecky is pretty much a league of her own.

Gary Hall Jr., himself a five-time Olympic gold medalist, expressed his admiration for the 19-year-old swimming wonder.

"Katie Ledecky is the greatest athlete in the world today, any sport, either gender. Having the top 11 times in the world in an event is just unheard of. Michael Phelps doesn't have the top 11 times in the world," he said.

Despite her phenomenal performance in the 400-meter freestyle, Ledecky remained candid and humble over her achievement.

"We set our goals for the week, and to finally hit one of them feels really good. Everyone wants to swim their best at the Olympics. I was just trying to set a personal best time, and for me, that just happens to be a world record," she said in an interview with The Washington Post.  

Currently, Ledecky holds 11 world records, holding the top spots in the 400-meter, 800-meter and 1500-meter freestyle. After beating her record in the 400-meter freestyle, Ledecky is now setting her eyes on an event that she is yet to dominate -- the 200-meter freestyle.

If she does manage to win the 200-, 400- and 800-meter freestyle in the 2016 Rio Olympics, she would become only one of two women who have been able to accomplish such a feat. The last time that happened was during 1968, when Debbie Meyer dominated the competition. 

Tags: 2016 rio olympics olympics Katie Ledecky 400-meter-freestyle world record