2025 World Championship Previews: McKeown vs. Smith Rivalry Continues in Women’s 100 Back

2025 World Championships

• July 27 – August 3, 2025 (pool swimming)
• Singapore, Singapore
• World Aquatics Championships Arena
• LCM (50m)
• Meet Central
• Live Results
• SwimSwam Preview Index

By The Numbers: Women’s 100 Backstroke

• World Record: 57.13 – Regan Smith, United States (2024)
• World Junior Record: 57.57 – Regan Smith, United States (2019)
• Olympic Record: 57.28 – Regan Smith, United States (2024)
• 2023 World Champion: Kaylee McKeown, Australia – 57.53
• 2024 Olympic Champion: Kaylee McKeown, Australia – 57.33

The longstanding backstroke rivalry between Regan Smith and Kaylee McKeown is set to continue in Singapore later this month, as both athletes gear up for the 2025 World Championships.

The two superstars have dominated the 100 back for the better part of five years now, maintaining a lock on the top two spots in the global rankings since 2020. Throughout their years of domination, Smith and McKeown have battled for the claim of fastest swimmer in the world in the 100 back, with the two alternating who holds the world record in the event.

The women’s 100 back is shaping up to be a stacked race in Singapore, as in addition to McKeown and Smith, the event will also feature powerhouses like Katharine Berkoff and Kylie Masse, among others.

On Top of the World: Smith vs. McKeown

For the last few years, ownership of the women’s 100 back world record has flip-flopped between Smith and McKeown; Smith broke it for the first time in 2019 (57.57), only for McKeown to break it in 2021 (57.45) and lower it again in 2023 (57.33).

Smith took the world record back at the U.S. Olympic Trials last summer when she threw down a time of 57.13, officially putting her back on top of the world. The fastest Smith has been since then is 57.28, which she posted as the lead-off on the 400 medley relay in Paris. Those performances made her the owner of the two fastest times in history, just ahead of McKeown.

So far this season, Smith has posted two sub-58 swims. She turned in a strong performance at the Pro Swim Series in Fort Lauderdale a few months ago, throwing down a season-best time of 57.46 to mark the fastest time in the world this season, before following it up with a 57.69 at the U.S. National Championships in June.

Regan Smith (photo: Jack Spitser)

Although she’s dipped into the 58 range a handful of times over the past few months, Smith has not been far off of her top times this season and should be in top form heading into the World Championships.

Smith may have claimed the world record in the 100 back last summer, but McKeown brought home the Olympic gold medal in Paris. McKeown posted a time of 57.33 to beat out Smith by just over .3 and tie her own lifetime best exactly, which she had set the year prior when she broke the former world record at the 2023 Swimming World Cup in Budapest.

Although she has not lowered her lifetime best since Budapest, McKeown tends to be a bit more consistent with her times than Smith. McKeown has been regularly turning in times in the mid-57 range for the past two years; she posted a season-best time of 57.65 at the Australian Open Championships in April and recently swam a 57.71 at the Australian Swimming Trials last month.

McKeown’s performance in April marks both the 2nd-fastest time in the world this season behind Smith and the only other swim under 58 so far this season.

Both women were the top qualifiers in the 100 back for their respective national teams, and between the two of them, they hold 23 of the top 25 performances of all time in the event.

Top 10 Performances of All-Time

1. Regan Smith – 57.13
2. Regan Smith – 57.28
3. Kaylee McKeown – 57.33
4. Kaylee McKeown – 57.33
5. Kaylee McKeown – 57.41
6. Kaylee McKeown – 57.45
7. Regan Smith – 57.46
8. Regan Smith – 57.47
9. Kaylee McKeown – 57.47
10. Kaylee McKeown – 57.50

As the current world record-holder, Smith is undoubtedly a frontrunner for the World Championship title in Singapore, but McKeown will certainly be doing her best to chase Smith down for both the victory and the world record.

From Paris to Singapore: The Olympic Backstrokers

A handful of this year’s World Championships qualifiers contested the 100 back at the Olympic Games in Paris last summer, showing their speed on the biggest international stage.

Team USA’s Katharine Berkoff will be one of the top contenders for a podium spot in Singapore, having won bronze at both the 2023 World Championships (58.25) and the 2024 Olympics (57.98). Having set a personal best time of 57.83 at the U.S. Olympic Trials last summer, Berkoff is #4 on the ranking of all-time top performers, just behind Canada’s Kylie Masse.

Berkoff recently posted a season-best time of 58.13 at the U.S. National Championships in early June, just .3 off of her lifetime best, which marked the 3rd-fastest time in the world so far this season. The last two seasons saw Berkoff turn in faster swims at the championship qualifying meets than at the international championships themselves, so it will be interesting to see if she can break that pattern this time around.

Kylie Masse (photo: Fabio Cetti)

Masse is a veteran on the racing scene and has been one of the world’s top performers in the 100 back for nearly a decade; she broke the world record in 58.10 back in 2017 and held onto that title for a year before it was broken by Kathleen Baker.

Masse lowered her best time to 57.70 in 2021 but has not improved upon it since then, although she has continued to shine at international competitions. She won silver at the Tokyo Games (57.72) and the 2022 FINA World Championships (58.40), and she placed 4th at both the 2023 World Championships (59.09) and the 2024 Paris Games (58.29). This season, Masse won the 100 back in 58.18 at the Canadian Swimming Trials, marking the 4th-fastest time in the world and putting her right on Berkoff’s tail heading into  World Championships.

Another Paris Olympian who qualified for the World Championships in the 100 back is semifinalist Roos Vanotterdijk from Belgium. Vanotterdijk, who finished 22nd in 1:00.95 at the 2023 World Championships, turned in a much stronger performance in Paris last summer to place 10th in 59.86.

In February, Vanotterdijk threw down a massive lifetime best of 58.97, knocking .65 off of her previous best time and marking her first time under 59. Since then, she has mostly been posting times in the high 59 range, but if she can turn in a swim closer to her February performance, then she should be able to land herself in the top eight.

Podium Threats

Carmen Weiler Sastre made a splash at the Spanish Summer Championships in June, breaking the national record in the 100 back in 58.83 and knocking well over half a second off her previous lifetime best (59.57). The swim marked her first time under 59 and launched her up the international rankings, as she now sits at #8 on the top times list for this season. With a handful of American swimmers ranked ahead of her who missed out qualifying for Worlds in this event, Weiler should be one of the top seeds heading into the competition.

Weiler has made significant strides over the past two seasons, going from finishing 21st at the 2023 World Championships in 1:00.87 to placing 9th at the Paris Olympics in 59.72. With a lifetime best that is now almost a full second faster than where she was two years ago and a new Spanish national record under her belt, Weiler is certainly in top form as she gears up for Singapore and could make a push for the podium.

The Canadian Swimming Trials saw an upset in the 100 back, as ASU alum Taylor Ruck overtook Ingrid Wilm to clinch the second qualifying spot in the event. Ruck was a semifinalist in this event at the Tokyo Olympics and placed 17th at the 2022 FINA World Championships but missed out on a qualifying spot for the 2023 championship and the 2024 Olympics to Wilm.

Ruck posted a season-best 58.93 at the Canadian Swimming Trials, her fastest swim since 2019 and only her third time ever breaking the 59 barrier. That performance marks the 10th-fastest time this season, close behind O’Callaghan, and would have landed her in the top four at both the World Championships in Fukuoka and the Olympics in Paris.

Taylor Ruck (photo: Jack Spitser)

Ruck’s lifetime best time of 58.55 from 2019 ties her with Kennedy Noble at #18 on the all-time top performers list, and her recent race seems to mark a return to top form heading into the World Championships. If she can post a performance similar to her swim from Trials or even faster, then Ruck should land safely in finals and could even make a push for the podium.

Just .03 behind Ruck on the ranking of this season’s top time is the Netherlands’ Marrit Steenbergen, who threw down a massive lifetime best time of 58.96 at the Dutch Long Course Championships in June and set a new national record in the event. Steenbergen knocked over 1.5 seconds off her previous best (1:00.50) from 2023 and launched herself up the world rankings.

Steenbergen has never raced the 100 back at a World Championships before, but with her stunning performance at the Dutch Long Course Championships last month, she could certainly make waves in Singapore if she chooses to add it to her lineup.

Finals Contenders

France’s Pauline Mahieu should be one of the top contenders to make it back for finals, having placed 6th at the 2023 competition in 59.72. Mahieu just posted a new lifetime best time of 59.13 at the French Elite Championships in June, shaving .17 off of her previous time (59.30) and narrowly winning the event by .03. Thanks to that performance, she now ranks 14th in the world for this season, putting her in a strong position to qualify for the final in Singapore.

Fellow French teammate Mary-Ambre Moluh will be looking to make a splash at Worlds this summer. Moluh, who wrapped up her freshman season at Cal-Berkeley in March, narrowly missed out on an Olympic qualification in the 100 back last summer but came back in style this year to snag the runner-up spot at the French Elite Championships.

She blasted into the wall just .03 behind Mahieu, throwing down a lifetime best 59.16 to punch her ticket to Singapore. Moluh’s only individual appearance at a long course World Championships was in the 50 back in 2023, where she placed 10th overall, so she will be looking to make a breakthrough this summer, especially after making significant strides in her performances over the past year.

Other considerable final threats in this event are Letian Wan and Xuwei Peng, both of whom represented China in Paris last summer. While Wan placed 12th in the 100 back in 1:00.06, just behind teammate Wang Xueer (59.89), she also helped China to a 3rd-place finish in the women’s 4×100 medley relay, turning in a 59.81 as the lead-off. Wan also turned in a strong performance at the 2023 World Championships in Fukuoka, taking 8th in 1:00.39 after posting a best time of 59.49 during the semifinals.

Letian Wan (photo: Jack Spitser)

Wan won the 100 back in 59.21 at the Chinese National Championships in May, marking the 16th-fastest time in the world this season, but she boasts a lifetime best time of 59.02 from the year prior. Wan tends to swim faster in the preliminary and semifinals heats at these competitions, so while she is certainly a top contender to make it to the final, she may not be bringing home a medal in this event.

Peng, meanwhile, narrowly missed out on qualifying for the 2023 Worlds and the Olympics in the 100 back, as she placed 3rd at the Chinese National Championships both years. She managed to snag the runner-up spot behind Wan in May, posting a time of 59.49 to punch her ticket to Singapore.

The last time Peng represented China in the 100 back at a World Championship was in 2022 in Budapest, where she tied for 7th with a time of 1:00.01. Since then, she has lowered her lifetime best to 59.32, which would have landed her in the final at both Worlds in Fukuoka and the Paris Games. Peng will be facing tough competition in Singapore, but if she can post a time around or slightly faster than her personal best, she has a shot at making it to the final.

Australia’s Hannah Fredericks qualified for her first World Championships in the 100 back after taking 3rd behind McKeown and Mollie O’Callaghan at the Australian Swimming Trials in a time of 1:00.40. With O’Callaghan opting for her usual freestyle events, Fredericks snagged the second roster spot in the 100 back.

Fredericks turned in a season-best time of 1:00.29 during prelims at Trials in June, but that did not crack the top 25 ranking of performers this season. Last summer, she set a lifetime best time of 59.44, which would have been fast enough to make the final at both the 2023 World Championships and the 2024 Olympics. With several swimmers posting 58s this season, Fredericks will certainly need to be in the mid-to-low 59 range in Singapore if she wants to have a shot at the final in this event.

The Netherlands’ Maaike De Waard is a seasoned veteran in the 100 back, having made it to the semifinals at the World Championships in 2022 (1:00.15) and 2023 (59.84) and at the Paris Olympics (1:00.22). De Waard turned in a season-best time of 1:00.19 during the preliminary heats at the Dutch Long Course Championships in June, before taking the runner-up spot behind Steenbergen in 1:00.65.

While De Waard holds a lifetime best time of 59.62 from April 2022, she has not been under 1:00 since her performance in Fukuoka in July 2023. De Waard should land safely in the semifinals at least, but she may be harder pressed to secure a spot in the final.

The Verdict

This event is undoubtedly stacked with impressive talent, but while there is always room for a surprise upset, this race seems like it will be all about Smith and McKeown. It’s hard to say for sure who will claim that gold medal, but we’re giving the edge to McKeown for this one.

Despite Smith holding the world record in the event and often outsplitting McKeown on the relays, she has rarely beaten McKeown for the titles in individual races. McKeown prevailed in the 100 back at both the 2023 World Championships and the 2023 Olympic Games; she tends to be the runner-up during the preliminary and semifinal heats before overtaking Smith in the final.

In fact, in all of the times that McKeown and Smith have gone head to head in a 100 back championship final, McKeown has not lost a race to Smith since 2018 at the Pan Pacific Championships.

This is an event that has probably seen the least disruption since the Olympic Games, so at the end of the day, we expect the results to look a lot like the Olympic Games at the top.

SwimSwam’s Picks

Dark Horse: Danielle Hill (Ireland) – Hill secured her ticket to Singapore at the Irish Open Championships in April, turning in a time of 1:00.67 during the semifinals to cement her spot. The performance came after she placed 16th in 1:00.40 at the Games last summer to slide under the World Aquatics ‘A’ standard. As Ireland’s national record-holder in the 100 back, Hill boasts a lifetime best time of 59.11 from May 2024, but that is the only time she has ever been under 1:00. She most recently turned in a time of 1:01.50, which is just .01 faster than her performance at the 2023 World Championships, where she finished 27th. If Hill manages to get back to top form and can throw down a swim closer to that low 59 range, then she could have a shot at the final.