FUKUOKA, Japan — Here's why Katie Ledecky is one of the greatest freestyle swimmers in the history of the sport: She is never quite satisfied.

The 26-year-old American won the 800-meter freestyle on Saturday at the world championships to become the first swimmer to win six golds in the same event at worlds. It was also her 16th individual world title, breaking a tie with Michael Phelps for the most golds at worlds.

She also is a seven-time Olympic gold medalist and the world record holder in both the 800 and 1,500.

But that winning time — 8 minutes, 8.87 seconds, which is the seventh-quickest she'd ever swum — wasn't quite good enough in her favorite event.

"I'm just always trying to think of new ways to improve. I mean I've already got everything turning in my head right now. I kind of wanted to be better than I was tonight," she said, twirling her right hand beside her right ear, trying to stir up ideas.

"I'm pretty tough on myself," she said. "But I think I have found the balance of being tough on myself but also having that grace."

The 800 was Ledecky's second individual gold following her win in the 1,500 free on Tuesday. She also took silver in the 400 free. Li Bingjie of China took silver in 8:13.31, and Ariarne Titmus of Australia got the bronze in 8:13.59.

"It's fun to leave a meet with your favorite event, and I just wanted to leave it all in the pool," Ledecky said.

It was only the fourth gold for the United States in the seventh of eight days in the pool. Meanwhile, Australia has been piling it on with 13 golds, matching its best at the worlds. Australia won three more golds on Saturday.

The Americans lead the overall table with 31 medals (16 silver), Australia has 20 and China 13.

Kaylee McKeown of Australia made history of her own with gold in the women's 200 backstroke. McKeown's victory gave her a sweep of all three backstroke events after earlier wins in the 50 and 100. She became the first swimmer to sweep all three backstrokes at the worlds.

It all made up for her disqualification earlier in the 200 IM.

"You can't change the rules," she said. "I got ruled out. It's just the cards I was dealt with and I couldn't do much more than that. So I just had to carry myself the best I could and channel all my anger and turn a huge negative into a positive."

Regan Smith of the United States picked up the silver in 2:04.94, while Peng Xuwei of China got the bronze in 2:06.74.

Sarah Sjöström of Sweden continued her dominance with gold in the 50 butterfly. The 29-year-old won in 24.77 seconds and has now won the event five consecutive times at the worlds. The win brought Sjöström's individual medals at the worlds to 20, equaling Phelps' mark.

Sjöström also broke her own record in the 50 free, going 23.61 in a semifinal heat. Her old mark was 23.67 set in 2017.

"There are not too many secrets," Sjöström said about her longevity. "Just do the work every day, go to practice, and stay humble."

Zhang Yufei of China, who took gold in the 100 fly, claimed the silver in 25.05, while American Gretchen Walsh got the bronze in 25.46.

Japanese fan favorite Rikako Ikee finished seventh (25.78) in the 50 fly but was greeted warmly by the home crowd.

The 23-year-old Ikee won six gold medals at the 2018 Asian Games and was expected to be a favorite in the Tokyo Olympics. But she was diagnosed with leukemia in February 2019. Her comeback continues to resonate with both the Japanese public and her fellow competitors.

Cameron McEvoy of Australia led all the way to capture the gold in the 50 free in 21.06. It was his first individual gold in the worlds or Olympics.

American Jack Alexy collected his second silver of the worlds in 21.57 to go with his silver in the 100 free. Benjamin Proud of Britian, last year's world champion, took the bronze in 21.58.

Caeleb Dressel won the event at the Olympics but did not qualify for the U.S. team. McEvoy's time was quicker than Dressel's winning time in Tokyo — 21.07.

Maxime Grousset of France won gold in the 100 fly in 50.14. The 24-year-old took the early lead and held on. Josh Liendo of Canada earned the silver in 50.34, while American Dare Rose made the podium with the bronze (50.46).

Ruta Meilutyte of Lithuania equaled the world record of 29.30 in her semifinal in the 50 breaststroke.

Australia won the 4x100 mixed freestyle relay in a world record of 3:18.83. The Americans took silver in 3:20.82, with Britain getting the bronze in 3:21.68. The relay is not an Olympic event. [Copyright 2023 NPR]