Kaylee McKeown into backstroke final at world swimming titles as Alex Perkins wins bronze

Australia's five-time Olympic gold medallist Kaylee McKeown has set up a showdown with US rival Regan Smith in the women's 100 metres backstroke final at the World Aquatics Championships in Singapore.

McKeown and world-record holder Smith went to head-to-head in Monday night's semifinals, with the American narrowly winning in a time of 58.21 seconds.

After the race, McKeown — who swam 58.44 — revealed she did not want to swim the race.

"I didn't actually want to do the 100 at this meet," she said.

"I just wanted to come in and do the relays and the 200 backstroke, so [I'm] putting myself out there for a little bit. Good to get the monkey off my back."

That monkey was the pressure McKeown felt she was putting on herself, as well as the media's expectations.

"I don't really care if I come first [or] if come last, I just want to find love for the sport again," McKeown said.

McKeown completed the 100-200m backstroke double at the Paris Olympics just months after Smith broke the Queenslander's world record at the US trials.

She said the experience was overwhelming.

"Off the back of Paris, I just found I was getting a bit consumed with the pressure and the nerves, not only [what] the media circulates, but [what] I put on myself," she said.

"So, I'm really just taking this year to get back into it, find my love for the sport again, because I don't ever want to lose that."

Asked whether she was succeeding in that mission to regain her love, McKeown responded: "Absolutely."

McKeown said she had benefited from making changes in her personal life.

"I've moved back to the Sunshine Coast now and it's been the best move that I could have done for myself," she said.

"I'm the happiest I've been outside the sport for a really, really long time and hopefully maybe not this year, but next year it will start showing in my swimming, too."

Not that her swimming is exactly bad, rather it is just not at a world-record level just yet.

"I think it would be boring if there wasn't a rivalry [with Smith]," McKeown said.

"It's the reason that swimming becomes competitive. That's all I've really got to say on that."

McKeown would not be drawn on her ambition for the 100m backstroke final, a race she did not want to swim.

"I don't care what anyone's telling me. I'm going to be really, really stubborn with this," McKeown said.

"I don't care what you guys [media] want to put on me. I'm just here to have a good time and have fun and, like I said, if that's coming last, if that's coming first, I'm here for a good time."

Perkins makes podium

It was a more subdued night for Australia in Singapore after the double gold success of Sunday night.

Australia's only medal was a bronze to Alex Perkins in the women's 100m butterfly.

Perkins was third in a time of 56.33 to finish behind US world record holder Gretchen Walsh, who set a championship mark of 54.73 in the final.

The bronze was Perkins's first individual medal at a World Aquatics Championships.

"I couldn't be happier, honestly," she said.

"I tried not to expect anything going into that final. I just wanted to put my best foot forward and be proud of what I've done.

"Coming away with a medal is just a bonus."

Walsh had been battling food poisoning and had pulled out of the women's 4x100m freestyle relay final the previous evening.

But on Monday she powered home to record the second-fastest time in history.

Perkins, swimming in lane three next to Walsh (lane four), said she did not dare to dream that the American great's upset stomach might give her an outside chance of victory.

"No, she's [Walsh] an incredible athlete. I knew she'd be in the race and wanting that individual world title, and I think that lifts the whole field," Perkins said.

"So I'm really happy she was there and I got to race alongside her. She's just incredible.

"[I] had a little chat to her in marshalling. She's lovely and humble."

Perkins, who turned 25 on Sunday, debuted for Australia at the 2022 Commonwealth Games in Birmingham.

She has won silver medals in relays at the Olympics and World Aquatics Championships as a heat swimmer.

Perkins said she had always seen herself as more of a trainer than a racer.

"I just feel like I trained at a level that was higher than I was racing, but now I really feel it's starting to reflect in my racing a little bit more," Perkins said.

Canadian Summer McIntosh made it two golds from as many events, winning the women's 200m individual medley.

McIntosh triumphed in a time of 2:06.69, which is a second slower than the world record she set at the Canadian trials.

But it was almost 2 seconds faster than American Alex Walsh, who finished second.

Eighteen-year-old McIntosh is contesting five individual races and two relays in Singapore.

Michael Phelps is the only swimmer to have won five individual gold medals at a single edition of the World Aquatic Championships, a feat he achieved when the event was held in Melbourne in 2007.

After claiming gold in the men's 4x100m relay, Australia's Flynn Southam (1:45.80) narrowly missed out on a place in the final of the men's 200m freestyle, finishing 10th fastest across the two semifinals.