GWANGJU, South Korea -- Adam Peaty became the first man to win a third 100-meter breaststroke title at the world swimming championships on Monday night, and a Canadian teenager grabbed a share of the spotlight by upsetting Swedish star Sarah Sjostrom in the women's 100 butterfly.
Katinka Hosszu of Hungary also added more gold to her collection.
Peaty won 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 is also the reigning 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.
Margaret MacNeil, 19, competing in her biggest international meet so far, surprised 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 dipped under her world-record pace on the first lap, while MacNeil was in fifth.
But MacNeil had 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 breast. Emma McKeon of Australia earned bronze in 56.61.
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.
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.
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.
After getting upset in the 400 freestyle on Sunday, Katie Ledecky competed in the morning preliminaries of the 1,500 freestyle. She breezed through the grueling race in 15 minutes, 48.90 seconds -- 2.69 seconds better than second-fastest qualifier Simona Quadarella of Italy.
The final is Tuesday night.