The Australian world record holder was in full control to touch in 3mins 57.49secs ahead of Canada's McIntosh (3:58.37) and decorated American Ledecky (4:00.86), who faded badly in the final 50m.

Known as ‘The Terminator’, Titmus will also swim the 200m and 800m in Paris. Ledecky has opted out of the shorter distance, focusing instead on defending her 800m and 1500m titles. McIntosh is also skipping the 200m free, instead prioritising the 200m and 400m medley and 200m butterfly.

Most, Germany's Lukas Maertens is surging to the men's Olympic 400m freestyle gold medal but always believed he would rise to the top. The 22-year-old was under a world record pace for 350m at La Defense Arena. It was Maertens' first Olympic medal after making his debut at the delayed Tokyo 2020 Games.

Most, a United States team spearheaded by Caeleb Dressel stormed to the men's 4x100m Olympic relay gold medal ahead of Australia on Saturday.

The quartet of Jack Alexy, Chris Guiliano, Hunter Armstrong and Dressel came home in 3min 09.28sec with Australia taking silver in 3:10.35 and Italy bronze in 3:10.70.

And Australia swam the second fastest time in history Saturday to clinch the women's 4x100m freestyle gold medal ahead of the United States at the Olympics.

Their team of Mollie O'Callaghan, Shayna Jack, Emma McKeon and Meg Harris proved too hot to handle, touching in 3min 28.92sec ahead of the Americans (3:30.20) and China (3:30.30).

It was the fourth successive Olympic gold Australia has won in the event, with the time second only to their own world record of 3:27.96 set last year.

-Paris Olympics swimming results on Saturday:

Men

400m freestyle

Final

1. Lukas Maertens (GER) 3:41.78

2. Elijah Winnington (AUS) 3:42.21

3. Kim Woo-min (KOR) 3:42.50

4. Samuel Short (AUS) 3:42.64

5. Guilherme Costa (BRA) 3:42.76

6. Fei Liwei (CHN) 3:44.24

7. Oliver Klemet (GER) 3:46.59

8. Aaron Shackell (USA) 3:47.00

Women

400m freestyle

Final

1. Ariarne Titmus (AUS) 3:57.49

2. Summer McIntosh (CAN) 3:58.37

3. Katie Ledecky (USA) 4:00.86

4. Erika Fairweather (NZL) 4:01.12

5. Isabel Gose (GER) 4:02.14

6. Paige Madden (USA) 4:02.26

7. Maria Fernanda Costa (BRA) 4:03.53

8. Jamie Perkins (AUS) 4:04.96

Women

4x100m freestyle relay

Final

1. Australia 3:28.92

2. United States 3:30.20

3. China 3:30.30

4. Canada 3:32.99

5. Sweden 3:33.79

6. France 3:34.99

7. Great Britain 3:35.25

8. Italy 3:36.51

Men

4x100m freestyle relay

Final

1. United States 3:09.28

2. Australia 3:10.35

3. Italy 3:10.70

4. China 3:11.28

5. Great Britain 3:11.61

6. Canada 3:12.18

7. Germany 3:12.29

8. Hungary 3:13.11