Katie Ledecky was forced to settle for bronze in the women's 400m freestyle Saturday as Ariarne Titmus claimed gold once again. 

The Australian defended her gold from Tokyo in a battle dubbed the 'Race of the Century, leading wire to wire. 

However, Ledecky wasn't just beaten out by Ledecky. The American failed to even clinch silver as Canadian phenom Summer McIntosh won her first Olympic medal. 

It was a highly-anticipate three-way duel, with the trio all having held the world record over the distance in the past three years.

In the much-hyped final, the Tasmanian-born 'Terminator' Titmus clocked three minutes 57.49 seconds to win from McIntosh (3:58.37) and Ledecky (4:00.86).

Earlier on Saturday, Ledecky had fired the first shot in her duel with Titmus, posting the fastest time the preliminaries. 

Titmus got off to a fast start but couldn't hold off the hard-charging Ledecky on the final lap but she wasn't making the same mistake in the evening. Not with gold on the line. 

It wasn't the first time the Australian has dethroned seven-time Olympic gold medalist Ledecky. 

Titmus exploded onto the scene - and into her prime - just ahead of  the postponed Tokyo Games in 2021, where at age 20, she became the first woman to beat Ledecky in an Olympic race.

It was the beginning of their rivalry. On that has followed them to Paris. 

The rivalry was turned up a notch this week, with the American slyly snubbing her rival before their battle for Olympic gold.

Ledecky, the most successful female swimmer ever with seven Olympic gold medals and 21 world championship golds, refused to say Titmus' name during a packed press event in Paris.

Until Saturday, the American superstar hadn't beaten the Aussie superfish in the 400m freestyle in five years - and couldn't bring herself to acknowledge Titmus personally, despite being her biggest threat to taking home the gold.

'I like my chances, but yeah that's me and I feel like I'm prepared and ready to race and that's all you can ask for,' Ledecky said.

'So I'm gonna give it my best shot and it's obviously a great field, top to bottom. Lots of people that have a chance so I'm just gonna put up a great race in the morning and at night and see where that lands me.

'They're great athletes and I've had the chance to race them quite a few times over the years now, especially Summer (McIntosh) being in the US training in the US and we've raced a lot the last couple of years.

'It's always fun to race the best and we have the top three times ever in that race so that just makes for a great field, great race.

'Those two have continued to raise the game, raise my game. I know that I have to bring my best. I think they know that they have to bring their best.'

Ledecky is looking to add to her haul of six individual gold medals - already the most by any female swimmer in Olympic history. She's a heavy favorite in both the 800 and 1,500 freestyle.