PARIS, France (AFP) — Ariarne Titmus dominated rivals Katie Ledecky and Summer McIntosh to retain her Olympic 400-meter freestyle title on Saturday while German Lukas Maertens surged to the men’s gold in the first day in the pool in Paris.

The decorated American Ledecky was gunning for revenge after the Australian dethroned her in Tokyo three years ago, but it was Titmus who again prevailed in an electric atmosphere at La Defense Arena.

The 23-year-old world record holder led from start to finish to hit the wall in three minutes and 57.49 seconds and remain unbeaten over the distance since 2019.

Ledecky had to settle for bronze after fading badly over the final lap, adding to her cache of 10 Olympic medals, seven of them gold.

Canadian teenager McIntosh grabbed silver after reeling in the American great to clinch her first Olympic medal, after coming fourth in Tokyo as a 14-year-old.

“I know what it takes to be a champion and I know how hard it is racing in these circumstances,” said Titmus, who came to Paris after swimming the second fastest time in history last month.

“An Olympic Games — it’s not really like anything else.”

“I probably felt the expectation and pressure for this race more than anything in my life, to be honest.”

It was billed as a blockbuster showdown, with Titmus, Ledecky and McIntosh sharing the 27 fastest times in history.

Known as “The Terminator,” Titmus will also defend her 200m title on the back of shattering the world record last month, while trying to prevent Ledecky winning a fourth straight gold over 800m.

Ledecky has dropped the 200m from her schedule but will be a strong favorite over 800m and 1500m, races she has long dominated.

“It feels good. It’s always good to get a medal for Team USA,” said Ledecky, 27.

“I wanted to be a little faster, but I can’t complain about a medal. I knew it would be tough.”

McIntosh is also skipping the 200 free, instead prioritizing the 200-400m medley and 200m butterfly.