There has been triumph and heartache in the Olympic pool for Aussies on Thursday morning (AEDT).

Kyle Chalmers and Zac Stubblety-Cook both won silver medals in freestyle and breaststroke.

But women’s favourites Mollie O’Callaghan and Shayna Jack failed to medal in their 100m freestyle, coming fourth and fifth respectively.

New world record

Kyle Chalmers has swum to a historic silver medal, coming second to China’s Pan Zhanle who set a world record to win the men’s 100m freestyle.

Pan clocked 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.

He has became only the second man to medal in three consecutive Olympics in that men’s 100m event.

Kyle Chalmers celebrates with Zhanle Pan, who smashed his own world record. Photo: Getty

Stubblety-Cook took silver in the men’s 200m breaststroke behind French megastar Leon Marchand.

The Paris-born Marchand collected two golds within an hour on Wednesday after earlier saluting in the 200m butterfly — he now has three golds at the Games.

Sated by silver, Chalmers said he believed his Chinese conquerer was drug-free.

“I do everything I possibly can to win the race and trust everyone’s doing the same as I am, staying true to the integrity of sport,” silver medallist Chalmers said.

“I trust that … he (Pan) deserves that gold medal.”

China’s team has been under increasing scrutiny since revelations 23 swimmers tested positive to a banned substance before the Tokyo Olympics Games, but were allowed to compete at those Games.

Pan was not in that group.

Chalmers said he was satisfied with his second-consecutive silver in the men”s equivalent after winning gold in the event at the 2016 Olympics.

Stubblety-Cook’s breaststroke silver came in the wake of Marchand, who pocketed two gold medals within an hour before a parochial home crowd at the Paris La Defense Arena.

Marchand won the 200m butterfly before his breaststroke victory and now has three golds medals at his home-town Games.

The Parisian saluted in two minutes 05.85 seconds and was 0.94 seconds ahead of Stubblety-Cook.

Women’s wipeout

Meanwhile, Australia’s Mollie O’Callaghan says she has to “suck it up” after missing the medals in the 100m freestyle final.

O”Callaghan finished fourth and compatriot Shayna Jack fifth on  Wednesday night.

“I expected a lot more,” O’Callaghan said.

“But at the end of the day you’ve got to suck it up and wait another four years.”

O’Callaghan entered the medal race as favourite and bidding to become just the third woman to complete a 100-200m freestyle golden double at the same Olympics.

But Swedish great Sarah Sjostrom trumped the field, winning in 52.16 seconds. The 30-year-old world record holder is racing at her fifth Olympics.

O’Callaghan (52.34) and Jack (52.72) failed to make ground on the last lap after turning in their finishing positions.

Mollie O’Callaghan missed out on a medal in the 100m freestyle. Photo: Getty

O’Callaghan beat teammate Ariarne Titmus for the 200m freestyle gold medal and also featured in Australia’s victorious 4x100m freestyle relay team at the Paris pool.

But the 20-year-old admitted suffering anxiety leading into the 100m final.

“I was really nervous heading into this, didn’t have a lot of sleep over the past few days,” she said.

“I tried really hard to manage myself and get up for this but I knew 100 free was going to be hard because it’s a lot about speed and that’s something I really lack in.

“I knew it was going to be at tough race … if you stuff something up, it costs you.”

Jack, also a part of Australia’s triumphant 4x100m freestyle relay team on Saturday night, missed the Tokyo Games three years ago after serving a two-year doping ban.

“I wanted to walk out, soak up the crowd and enjoy my family being in the stands,” Jack said.

“I tried to reflect but absorb the fact I’m here as an Olympian. A couple of years ago I never thought that would be possible.”

-with AAP