Ariarne Titmus dominated rivals Katie Ledecky and Summer McIntosh to retain her Olympic 400m freestyle title on Saturday as German Lukas Maertens surged to the men’s gold on day one 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 3mins 57.49 secs 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 favourite 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 with a medal. I knew it would be tough.” McIntosh is also skipping the 200 free, instead prioritising the 200-400m medley and 200m butterfly. Overwhelmed: Maertens was equally untouchable in the men’s 400m, under world record pace for much of the race before tiring in the final stretch to touch in 3:41.78 ahead of Australia’s Elijah Winnington and South Korea’s Kim Woo-min. “Means everything to me –- you can see my progress in performance… I am extremely happy and just overwhelmed,” said Maertens. “I can’t put into words what I am feeling now.” The German arrived in Paris more than a second quicker than anyone else this season after clocking the best time since 2012 in April, just 0.26 seconds away from Paul Biedermann’s super-suited world record. Australia again proved unstoppable in the women’s 4x100m freestyle relay to remain undefeated at the Olympics since 2012. Boasting a formidable line-up of Mollie O’Callaghan, Shayna Jack, Emma McKeon and Meg Harris, they stormed home in 3:28.92, the second quickest in history behind their own world record. The United States took silver and China bronze. Anchored by Caeleb Dressel, the United States took out the men’s 4x100m relay ahead of Australia and Italy to continue their long domination of the event. In semi-final racing, Adam Peaty posted 58.86 in the 100m breaststroke to lead the way in his bid to become only the second man to win three straight gold in the same individual event after Michael Phelps. Back in top form after a break for mental health troubles, Peaty has lowered the world record five times over an extraordinary career. Key rival Qin Haiyang, reportedly among the 23 Chinese swimmers embroiled in a doping scandal that rocked the sport this year, was second quickest in 58.93. American world record holder Gretchen Walsh was in control of the women’s 100m butterfly semi-finals, scorching to the third fastest time ever with an eye-catching 55.38. The 21-year-old shattered Sarah Sjoestroem’s eight-year-old world best at the US trials and now owns the three top times ever swum. Her teammate Torri Huske was second fastest in 56.00 ahead of Tokyo silver medallist Zhang Yufei, also allegedly among the swimmers caught up in the same doping scandal as Qin.