France's Paris Games poster boy Leon Marchand achieved what no swimmer has done before by winning the 200m breaststroke and butterfly golds on the same night - and both in Olympic record times - at his home Games.
Less than 10 minutes later, China's Pan Zhanle obliterated his own 100m freestyle world record - humbling a slew of champion rivals.
But the loudest noise was reserved for Marchand at the La Defense Arena as the 22-year-old rewrote the script on what was previously thought possible by becoming the first to medal in both of the demanding disciplines.
Even US great Michael Phelps, whose coach now works with the Frenchman, did not achieve that.
With the crowd chanting his name at every stroke -- "Leon, Leon" echoing around the arena -- Marchand led every metre of the breaststroke before touching out in two minutes 05.85 seconds.
The world record, set by China's Qin Haiyang last year, stands at 2:05.48 and Marchand was set to beat that up to the 150 metre mark.
Australia's Zac Stubblety-Cook, the 2021 champion in Tokyo, had to settle for silver while Caspar Corbeau of the Netherlands took the bronze.
Marchand, who won the Individual Medley on Sunday, sent sound levels off the scale from the moment he stepped onto the pool deck.
In the butterfly race he beat Hungary's world record holder and reigning champion Kristof Milak into second place, with Canada's Ilya Kharun finishing third.
Unlike in the later breaststroke, Marchand was behind until the final length when he overpowered Milak and surged past to win.
He returned for the podium ceremony, saluting the cheering crowd as the "Marseillaise" national anthem sounded, and then made a quick exit to prepare for the breaststroke.
Such was the sense of anticipation ahead of the later event that the poolside volunteers removing the athletes' clothing boxes left more hurriedly than usual, sprinting even, to catch the race on television.
All over town crowds waited and watched as history unfolded, spectators at the table tennis venue singing the anthem after Marchand's first gold of the night.
To win both titles was a simply astonishing achievement. To do it at a single Games even more remarkable. To take double gold on the same night, with a medal ceremony in between, truly the stuff of fiction.
Pan smashes world mark
Nineteen-year-old Pan's 100m freestyle time of 46.40 seconds shaved an incredible 0.40sec off his previous mark set at the world championships in Doha in February when he announced himself to the world with a stunning relay leadoff swim.
Australia's silver medallist Kyle Chalmers finished a yawning 1.08 seconds behind the incredible Pan, while David Popovici finished a further 0.01 second behind for the bronze.
There was no easing in for Pan who took off like a rocket and mowed down the opening 50 metres in an outrageous 22.28sec.
The Chinese sensation blew any hopes Chalmers and Popovici might have had of catching him out of the water as he stretched his lead and flew to the wall.
A doping storm has followed China's swim team to Paris after revelations in April that 23 Chinese athletes had tested positive for a banned heart medication but were allowed to swim at the Tokyo Games.
China said the athletes were victims of contamination from a hotel kitchen, and an independent review backed the World Anti-Doping Agency's handling of the case.
China was then plunged back into the spotlight on Tuesday after the New York Times reported that two swimmers in 2022 had tested positive for a banned steroid but had provisional suspensions lifted when the results were also blamed on contaminated food.
Teenager Pan rose above the acrimony, however, to earn his first Olympic gold medal some five months after winning the world title.
Chalmers, the gold medallist at Rio 2016, took his second silver in the event, having finished runnerup behind Caeleb Dressel at the Tokyo Games.
Popovici, who previously held the world record before Pan took it at Doha, added the bronze to his 200m freestyle gold medal at Paris.
- Reuters