Ariarne Titmus has ended the reign of American superstar Katie Ledecky in one of the best swims ever produced by an Australian.
It was history. It was magic. It was one of Australia's greatest Olympic moments.
The 20-year-old Queenslander had to come from behind in the final 150m, but she swam the perfect race to come over the top of her rival in a thrilling 400m freestyle final.
She reeled in the greatest of all time to become one of the greatest of all time. It was the first time Ledecky had ever lost in an individual event at the Olympics – adding her second silver medal to her five gold medals.
Aussie legend Ian Thorpe said Titmus "delivered".
"This is amazing. Look at this moment for Ariarne.
"Against the best female swimmer that the world has ever seen. What a performance."
Her coach Dean Boxall went completely ballistic when watching on from the grandstand inside the Tokyo Olympic Aquatic Centre as Titmus did what many thought was impossible – and he embodied the mood of the entire country.
Titmus hit the front for the first time with just 50m to go – and held on to win by 0.66 seconds.
It was the biggest headline moment for the Olympics so far with the world sitting on the edge of its seat to see if Ledecky's reign was coming to an end.
The American goliath had been untouchable in the event before Titmus stunned the world to win at the 2019 world championships.
She did it again on Monday to win Australia's second gold medal of the Tokyo Games with the second quickest 400m ever swum by a woman. It was a personal best, a new Olympic record and a new Australian record.
Her time of 3:56.69 was just 0.23 seconds short of Ledecky's record.
There was a touching moment on the side of the pool after the race when Ledecky – the world record holder and five-time Olympic champion – congratulated Titmus.
The Aussie revealed what was said in the private exchange when interviewed on the pool deck.
"I thanked her. I wouldn't be here without her," she said.
"She set this incredible standard. All credit to her for the swimmer she is. I've been trying to chase her. Really exciting now we have this battle going. It's really fun to race."
It's easy to see why it was the most highly-anticipated showdown in the pool at this Games.
"I can't believe I pulled it off," Titmus said.
"I can't believe it. I'm trying to contain my emotions. I have the 200m (freestyle) tonight. Oh my gosh. I can't believe it."