Mollie O'Callaghan and Ariarne Titmus tried to contain their emotions, but both burst into tears after the epic 200m freestyle, when the dynamic of being training partners became clear.
O'Callaghan won his first individual gold and fourth place overall in an Olympic record time of 1:53.27, after sweeping the field in the final lap.
Titmus likes to give it his all, but at the 150m mark he didn't have enough of a lead and O'Callaghan caught up with him with a sharp final turn, finishing half a second ahead.
The training partners hugged after the race, shared the top step of the podium and paid tribute to their coach Dean Boxall.
O'Callaghan, 20, was all class, describing Titmus, 23, as an “absolute cannon”.
“He runs like an absolute beast,” O’Callaghan said. “And it’s an honor to train alongside him and have such a fantastic team around us.”
But the stark reality that the two fastest women in the world came not only from the same country, but also from the same training team, became apparent after the race.
Titmus was the reigning Olympic champion and O'Callaghan is the world champion, having broken the long-standing supersuit record at last year's world titles.
Both broke that world record at this year's Australian trials, but Titmus won the race, so she holds both the 200m and 400m world records.
O'Callaghan was in tears after being beaten during the selection process, but recovered and went on to win her first individual Olympic title.
Titmus was striving to become immortal in swimming: a victory would make her the only Australian to win four individual golds and the 13th swimmer to do so.
She would also become the first swimmer to complete the 200-400 meter freestyle double in two consecutive Olympics.
But instead of history, it was tears for Titmus. It is understood that Titmus responded by breaking down backstage and answering only one question in the mixed media zone.
After collecting their medals, Titmus and O'Callaghan became emotional and shed tears during poolside interviews.
“They're tears of joy, honestly,” Titmus said. “I don't know. It's really hard to hold back emotion in these situations.
“I know what it means to be an Olympic champion. I'm really happy for her. And I'm really happy to be on the podium.
“I'm an Olympic champion forever in the 200 and 400 meters and I gave it my all. I don't know why I'm crying. I'm really happy with the silver. It's hard to hold on to it, so it's just coming out now.”
O'Callaghan began to cry as she told Australian swimming great Giaan Rooney how much it meant to her to win in front of her parents.
“I'll let it settle at the end,” he said.
“Seeing my mom and dad, it hit me a little bit. I swim mainly for them. They put a lot of time and dedication into my swimming and when I was a kid.
“I wouldn't be here without them. I probably shouldn't cry now, it's not the end of the meeting. I'm lucky to have them with me and my support team.”
Stan Sports Olympics Daily host Tara Rushton said: “It looked like it was hard for Ariarne to watch in the cold light of day, so much so that she almost had to hold back her emotion at the time.”
Grant Hackett added: “It's tough, you're standing next to the winner you wanted to beat.
“Let's remember that just a few weeks ago Ariarne broke the world record in this race, by over a second, so she's probably sitting there reflecting on her performance and thinking, 'If I could have done what I did six weeks ago, or even just half a second behind, I'd be here as the Olympic champion in the women's 200m freestyle.'”
Coach Dean Boxall has 10 swimmers, a quarter of the Australian swimming team, in Paris and has somehow managed the Titmus-O'Callaghan dynamic as best he can. They rarely face each other in training and he gives them separate pre-race pep talks.
Karl Stefanovic said on Nine: “It's so awkward, isn't it? When your main competitor and training partner and you are going head to head for a gold medal at the Olympics. It's crazy.
“But it's nice to see those pictures.”
Stefanovic said: “I think Arnie felt a little uncomfortable” when Titmus called her to the top step of the podium to sing the national anthem together.
“(But) it's Mollie's time, this is what she wanted.”
There were even more touching scenes when cameras captured Titmus and O'Callaghan's parents embracing each other at the Defense Arena in Paris.
O'Callaghan has now won four golds by the age of 20: Ian Thorpe and Murray Rose were 21 when they achieved the same feat.
And she could match Emma McKeon's haul of six by winning the 100m freestyle and the 4x200m freestyle relay.
Titmus still has a chance to win a fourth individual gold in the 800-meter freestyle, where she will have to prevent Katie Ledecky from winning the race for the fourth consecutive time.
