Katie Ledecky cruised into the finals of the 400m freestyle Saturday as she kickstarted her Olympic campaign.  

Ledecky fired the first shot in her duel with Ariarne Titmus, posting the fastest time the preliminaries of the women's 400m freestyle Saturday as the swimming competition began at the Paris Olympics.

In one of the most highly anticipated events of the games, Ledecky claimed the prime No. 4 lane for the evening final with a time of 4 minutes, 2.19 seconds.

Titmus, the Australian star know as 'The Terminator,' got off to a fast start but couldn't hold off the hard-charging Ledecky on the final lap. 

Titmus posted the second-fastest time of the heats in 4:02.46, setting up a side-by-side showdown with the American in the evening final.

Titmus is the reigning Olympic champion in the 400 free, knocking off Ledecky at the Tokyo Games three years ago. The Aussie also holds the world record of 3:55.38 - a sign that she's got a lot left to give in the final.

The rivalry between Ledecky and Titmus 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. 

Also keep an eye on Canadian phenom Summer McIntosh, who should be in the medal mix after going 4:02.65 in the prelims for the fourth-fastest time. She was just behind New Zealand's Erika Fairweather (4:02.55).

Tokyo bronze medalist Li Bingjie and Chinese teammate Liu Yaxin finished ninth and 10th, respectively, and failed to advance to the final. Their team has been under intense scrutiny after reports that nearly two dozen swimmers tested positive for a banned substance before the 2021 Olympics but were not sanctioned.