PARIS, France (AFP) — Rising star Mollie O’Callaghan upstaged fellow Australian Ariarne Titmus to clinch the Olympic 200m freestyle gold medal while Canadian prodigy Summer McIntosh blitzed the field to be crowned 400m medley champion.

On a bumper night of medal action at La Defense Arena, Romanian teenager David Popovici won a frantic men’s 200m freestyle and Italy’s Thomas Ceccon the 100m backstroke.

South Africa’s Tatjana Smith rounded out a golden evening with a thrilling victory in the women’s 100m breaststroke.

O’Callaghan is known for her dynamic finishing power and that came to the fore once again.

Hong Kong’s Siobhan Haughey led through 150 meters with Titmus on her heels before O’Callaghan turned on the afterburners to bring it home in an Olympic record of one minute and 53.27 seconds.

Defending champion and world record holder Titmus, who won the 400m title on Saturday, was second in 1:53.81 and Haughey third.

“It’s such an honor to be with everyone, and compete against Arnie. She races like an absolute beast,” said O’Callaghan, who shares the same coach as Titmus.

“It’s an honor to train alongside her and have such a great team around us.”

It was the 20-year-old’s fourth Olympic gold medal, but her first in an individual event after making her mark as a relay swimmer in Tokyo.

Since then she has blossomed, winning the 100m and 200m at the 2023 world championships and smashing Italian great Federica Pellegrini’s 14-year-old 200m world record before Titmus took it away in June.

McIntosh also burnished her already glowing reputation with a dominant 400m medley.

The 17-year-old world record holder powered to the wall in 4:27.71 — the fourth-fastest time ever — to outpace American pair Katie Grimes (4:33.40) and Emma Weyant (4:34.93).

It was the Toronto swimmer’s second Paris medal after taking silver behind Titmus in the 400m free.

She is also favorite in the 200 medley and a serious contender in the 200m butterfly as she hovers on the edge of superstardom.

McIntosh, who made her Olympic debut in Tokyo as a 14-year-old, lowered her own world record in May when she clocked 4:24.38 and was always in charge.

“Very happy to get the job done, to stand on top of the podium and get the gold medal,” she said.

“I’m really just trying to soak up every single moment.”