A new Olympic 100m backstroke champion will be crowned with the incumbent Hungarian superstar, Katinka Hosszu, turning her focus to other events at the Games.
The event will boast a loaded field of rising young stars and seasoned campaigners looking to claim the vacant Olympic title.
The only three women to have dipped under 58 seconds in the women's 100m backstroke have already set the pool ablaze ahead of the final that promises to be a mouth-watering affair.
Australian world-record holder Kaylee McKeown leads the charge with American Regan Smith and her northern neighbour Kylie Masse of Canada breathing down her neck.
The trio lived up to hype over the first few days of swimming at Tokyo 2020 setting an unprecedented three consecutive Olympic records in their respective heats. First Masse, then Smith, before McKeown had the last laugh lowering the marks set by her rivals. The tit-for-tat battle over the Olympic record continued in the semi-finals, where Smith improved on it one more time ahead of the final.
The stage is set for one of the most exciting races in the pool. We take a look at the three top contenders for the coveted Olympic title in Tuesday's finals at the Tokyo Aquatics Centre.
The teenage phenom
Australian teenage phenom Kaylee McKeown will have a busy time at the Games, where she will be racing the 200m individual medley and the 100m and 200m backstroke events.
The 19-year-old will be looking to convert her world-record form in the 100m backstroke into Olympic gold and goes into the global showpiece as the resounding favourite.
McKeown's rise in the global swimming ranks has been nothing short of phenomenal, and she is expected to claim multiple medals at these Games.
She will head into Tokyo 2020 brimming with confidence after setting a world record at the Australian Olympic Trials in Adelaide, Australia, in June. McKeown touched the wall in a time of 57.45 seconds, chopping 0.12s off the mark US swimmer Regan Smith set at the 2019 World Championships.
The Aussie sensation has consistently dipped below 58 seconds since December 2020, highlighting her favourite tag.
"I looked [up], and I was like 'Oh surely not...'" McKeown said. "It's a good surprise ... pretty stoked with it, not going to lie. I wasn't expecting to come out and do that swim this morning.
"I rock up to the meet and do the best I can. It's a pretty outstanding world record (Smith's record) to be chasing, and there are a lot of girls out there who are still chasing those times."
The world champion
Former world record-holder Kylie Masse has the championship and Olympic pedigree after winning the bronze medal in Rio 2016.
The 25-year-old Canadian goes into the Games as the two-time defending world champion in the 100m backstroke and boasts the fourth-fastest time ever in the event.
Masse made waves at the 2017 FINA World Championships in Budapest, where she became Canada's first female global swimming champion hitting the wall in a world-record time of 58.10. That time has since been lowered by US swimmers Kathleen Baker and Smith before McKeown's latest effort. Baker has been ruled out of racing the 100m backstroke, otherwise the event would have seen four recent world record holders go toe to toe.
Masse joined the sub-58 seconds club at the Canadian Olympic trials racing to a new personal best of 57.70, taking 0.40s off her previous national record. In the process, she became only the third female swimmer to dip under 58 seconds.
"I think it's amazing seeing all the fast times around the world," Kylie Masse told Swimming World Magazine. "I've tried to stay in the present moment about what's going on in our own country, and I've had to accept that this whole year and a half, you can only control competitions and training in our own country. I've just been focusing on myself and the 58 barrier, I've been champing at the bit to break for a few years now, and it feels amazing to have done that."
Better known for prowess in the 200m backstroke, Smith will also be looking to stake a claim for the title in the 100m event.
Smith rose to prominence at the 2019 world championships in Gwanju, South Korea, where she won the 200m backstroke title. In the semi-finals, she smashed the world record Missy Franklin set in London 2012, clocking a time of 2:03.35.
She highlighted her abilities in the 100m backstroke when she set a world record of 57.57 swimming the lead-off leg in the women's 4x100 medley relay.
The 19-year-old Smith clocked the fourth-fastest time this year with the 57.92 she posted at the US Olympic trials.
"So touching the wall was like a shock and so much relief and just so much happiness. It's very surreal (qualifying for the Olympics)," Smith told Team USA.
"It still hasn't sunk in. But I'm just I'm very glad that that race is behind me now."