Australian swimming star Kyle Chalmers has denied suggestions he will retire after the Paris Olympics after winning a silver medal in the men's 100m freestyle final.

China's Pan Zhanle set a world record to win the gold medal in the event, clocking 46.40 seconds, with Chalmers posting 47.48 in Thursday morning's final.

Chalmers won gold in the event at the 2016 Rio Games and silver three years ago at the Tokyo Olympics.

Following the race, the 26-year-old wasted no time in shutting down suggestions that the freestyle final was his last individual Olympic event for Australia. 

He will be 30 years old when the next Olympic Games take place in Los Angeles in 2028.

"This is not my last individual event," he told Nine.

"I'm not retiring any time soon.

"I did everything I possibly could and I'm really proud."

A phenomenal final 50m allowed Chalmers to join Pan and the third-placed David Popovici on the podium after he was eighth off the blocks and eighth at the turn.

But even Chalmers' superhuman finishing could not overrun Pan, who broke his own world record of 46.80 from Doha earlier this year by 0.40 of a second in the first world record of these Games in the pool.

Stubblety-Cook hails the emergence of French superstar Marchand

Chalmers was not the only Australian male to be beaten by a freakish swim on Thursday morning, after Zac Stubblety-Cook was also forced to settle for a silver behind French superstar Leon Marchand in the 200m breaststroke final. 

Stubblety-Cook said he felt like he was a rugby game, not an Olympic swim meet.

He hailed the emergence of French hero Léon Marchand as "awesome" for swimming — despite it costing him another Olympic gold medal.

"It didn't feel like a swim meet," Stubblety-Cook said.

"It felt like at a rugby game … you can't hear yourself think.

"A crowd I'll never swim in front of that big again, it's awesome for the sport."

Marchand is now a triple gold medallist at his home Games and his every appearance has come amid wild backing from a 17,000-strong crowd at the Paris La Defense Arena.

The Frenchman won two golds in a one-hour span on Thursday morning, his second triumph denying Stubblety-Cook consecutive Olympic titles in the breaststroke event.

And the Dolphin said the best was yet to come from the 22-year-old Marchand, who is the French face of their Games.

"He's got a motor and he's hungry … he is probably on the cusp of being arguably the greatest swimmer to come," Stubblety-Cook said.

"We're only just seeing the beginning of Léon.

"It's his moment. And maybe if it was someone else, I wouldn't be as happy for him.

"But I'm stoked for him to have that moment in front of a home crowd, for him to soak that up is awesome and see him achieve that.

"I can't complain."

With AAP