KAZAN, Russia

There’s no stopping Katie Ledecky. The 18-year-old American virtually raced herself at the world swimming championships, and she was unbeatable.

Ledecky ended her meet in spectacular style Saturday night, lowering her own world record by 3.61 seconds in the 800-meter freestyle for her fifth gold medal.

She swam the 16-lap race in 8 minutes, 7.39 seconds, bettering her time of 8:11.00 set last year on home soil.

“I knew that I was capable of going sub-8:10,” she said, “so to go 8:07 means a lot.”

Ledecky completed a sweep of the 200, 400, 800 and 1,500 freestyles in Kazan. She swam the anchor leg on the victorious 4×200 free relay, too.

“It’s really neat to say that you’ve done something nobody has done before,” Ledecky said. “I’ll enjoy this for a few days and then I’ll get back to work and hopefully there’s more to come.”

She improved her results from two years ago in Barcelona, where she won four golds and set two world records. In Kazan, she won the 400 by 3.89 seconds, the 800 by 10.26 seconds and the 1,500 by 14.66 seconds, taking down her old world record in the preliminaries and the final.

Her closest race was the 200 free, when she rallied from fourth to win by 0.16 seconds.

“It could have been really tiring and it was,” Ledecky said. “But I recovered very well. I did what I needed to do to set myself up well each time that I got up on the blocks. I’m just proud of how I handled my races and how all this week has gone.”

Chad le Clos defended his title in the 100 butterfly, rallying late to edge Laszlo Cseh of Hungary in the absence of Olympic champion Michael Phelp.