GWANGJU, South Korea (AP) — Adam Peaty became the first man to win a third 100-meter breaststroke title at the world swimming championships on Monday night. Katinka Hosszu of Hungary also added more gold to her collection.

Peaty claimed the title in 57.14 seconds, a night after he became the first man to break 57 seconds in the semifinals. The British swimmer was under his own world-record pace at the turn before coming home a full body-length in front and 1.32 seconds ahead of teammate James Wilby.

In the semis, Peaty was timed in 56.88. He's also the current Olympic champion.

"That'll fuel me for next year because I know how bad I want to clear 56 even faster now," Peaty said. "I know exactly how to do it but I've obviously run out of opportunities here."

Wilby touched in 58.46. Yan Zibei of China was third in 58.63.

Hosszu extended her dominance in the women's 200 individual medley, claiming her record fourth title. That's the same number of times she's won the 400 IM.

"It might seem just another gold medal but for me it's really special to be here and be able to win," said Hosszu, who last year filed for divorce from her husband and training partner. "It's been a tough journey."

Nicknamed "The Iron Lady" for her relentless workload, Hosszu won in 2 minutes, 7.53 seconds.

Ye Shiwen of China finished 1.07 seconds back in second. Sydney Pickrem of Canada took bronze.

Canada's Margaret MacNeil, a 19-year-old competing in her biggest international meet so far, upset Sarah Sjostrom in the women's 100 butterfly, an event the Swede had won four times.

"I was really hoping just to get on the podium," MacNeil said, "but getting a gold is just unbelievable."

Sjostrom took it out strong, dipping under her world-record pace on the first lap, while MacNeil was in fifth.

But MacNeil roared back with the fastest closing lap — 29.06 — of the eight-woman final and touched first in 55.83.

Sjostrom was second in 56.22, denied a record fifth title in the 100 fly. Emma McKeon of Australia earned bronze in 56.61.

"Obviously, I would be more happy with a gold medal," Sjostrom said.

After receiving their medals, the three women gathered on the top podium spot and raised their palms to the crowd, displaying a message to ailing 19-year-old Japanese swimmer Rikako Ikee.

"Rikako never give up" it read, with hearts decorating their palms. Sjostrom came up with the idea.

Ikee announced in February that she has leukemia. She was the world junior champion in the 100 fly and had the fastest time in the world last year. She is aiming to return in time to compete in the Tokyo Olympics.

"We're hoping this will show that we're supporting her and we're here if she needs anything," said MacNeil, who swims at Michigan.

The United States won its first-ever gold in the men's 50 fly, a non-Olympic event. Caeleb Dressel's time of 22.35 set a championship record and earned him a ninth career world title.

Two years ago, Dressel won seven golds to equal Michael Phelps' record at a single worlds. The 50 fly was the only event Dressel failed to win in Budapest.

Dressel tied a bandana belonging to a former high school mentor who died on the ribbon that was placed around his neck as a way to carry her memory with him.

"That's faster than two years ago and a better place than two years ago," Dressel said. "It's good, good for Team USA and I'm glad I can be a part of keeping that ball rolling."

China's Sun Yang was back in the pool for the 200 freestyle semifinals a night after winning the 400 free. He qualified second-fastest behind Clyde Lewis of Australia. The final is Tuesday night.

Earlier Monday, FINA's executive board met in Gwangju to discuss Mack Horton's podium protest against Sun and decided to send a warning letter to Swimming Australia and to Horton.

"While FINA respects the principle of freedom of speech, it has to be conducted in the right context," the board said in a statement.

Horton refused to take his spot on the medals stand or shake Sun's hand after finishing second to the Chinese star in the 400 free. The Aussie swimmer is angry that Sun, who served a three-month doping suspension in 2014, is being allowed to compete in Gwangju before he faces a Court of Arbitration for Sport hearing in September that could potentially end his career.

After getting upset in the 400 freestyle on Sunday, Katie Ledecky's lone race was the morning preliminaries of the 1,500 freestyle. She breezed through the grueling race in 15 minutes, 48.90 seconds — 2.69 seconds faster than second-fastest qualifier Simona Quadarella of Italy.

The final is Tuesday night.

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This story has been corrected to show Margaret MacNeil won the women's 100 butterfly, not 100 breaststroke.

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