BUDAPEST - The world championships came alive on Tuesday as Lilly King of the United States won the women's 100m breaststroke title in one of three record-setting swims at the end of a breathtaking evening session.

Adam Peaty of Britain continued his breaststroke trailblazing with his second world mark of the day to reach the 50m final and Canada's Kylie Masse produced a world-best time to win the women's 100m backstroke gold medal.

And there was more history for Katie Ledecky following her routine gold in the women's 1500m freestyle as the American claimed the 12th world title of her short career.

The evening will be long remembered by Olympic champion King, who clocked 1min, 4.13sec to overhaul the world record mark set by Lithuania's Ruta Meilutyte in 2013.

King held off the threat of Russian rival Yuliya Efimova, in a race billed as a grudge rematch of their acrimonious Olympic final, and the US secured a memorable 1-2 as Katie Meili touched for silver in 1min, 5.03sec.

"That race was always going to be a showdown, an exciting dog fight," said King.

"We get a lot of rivalries like this in football, basketball, swimming where we see a lot of really nice people being really nice.

"That's great and all but it's not my personality. I'm spunky, I'm confident and I'm not going to not be myself before a race."

King, 20, has voiced her disapproval at Efimova being allowed to compete at the global level after the Russian was twice caught using banned substances.

The spiky relationship continued in Budapest, with King celebrating her world record wildly and failing to make eye contact with Efimova, who had to settle for bronze.

Meanwhile, a disbelieving Peaty became the first man to dip below 26 seconds in the 50m breaststroke a day after winning the 100m title.

By touching in 25.95, he lowered his record mark from the morning's heats by a massive 0.15sec.

"I was on such a high from this morning and it was so hard to ignore the fact that I did a world record and try to get myself emotionally ready," Peaty said.

Canada's Masse, the bronze medalist at last year's Rio Olympics, produced an outstanding world record swim of 58.10sec as Australia's quiet world championships continued with Emily Seebohm failing to defend her title.

Kathleen Baker of the US, the Olympic silver medallist, had to settle for the same prize as she beat Seebohm by 0.01sec.

The dominant force in women's distance swimming is Ledecky, who clocked 15min, 31.82sec to win the 1500 by 19 seconds over Spain's Mireia Belmonte.

It was a grueling schedule for Ledecky who, 30 minutes later, posted the best qualifying time in the women's 200m freestyle ahead of Italy's Federica Pellegrini.

"I was just in a really good mental spot going into the 200 and I felt like I could treat it like any other race," said Ledecky.

"I kind of ignored the fact that I'd swum the mile and just got up and raced as well as I could."

Reuters