Joseph Schooling sensationally upset Michael Phelps in the 100m butterfly on Friday to seize Singapore's first ever Olympic gold medal at the Rio Games.
The 21-year-old Asian champion denied Olympic icon Phelps a fourth straight victory in the event, leading from start to finish to win in an Olympic record of 50.39sec.
Phelps, sixth at the turn, couldn't pull off one of his trademark comebacks, but he had plenty of company on the second step of the podium as his longtime rival Laszlo Cseh of Hungary and South African Chad le Clos both matched his time of 51.14sec in an astonishing three-way tie for silver.
The only other three-way tie for Games silver came back in 1968, in the women's speedskating 500m.
"It's wild," said Phelps. "Chad and I have had some races over the last four years and Laszlo and I - I can't even remember when I first raced him... so it's kind of special and a decent way to finish my last individual race."
The tie with Phelps was the closest Cseh has come to the US star in Olympic competition. In three prior Games the Hungarian had claimed five medals, all silver or bronze in races won by Phelps.
Phelps's rivalry with Le Close blossomed more recently, at the 2012 London Games where the South African beat Phelps in the 200m butterfly only to fall to him in the 100m fly.
Victory in Friday's fly would have given Phelps a 14th individual Olympic title, but Schooling was too strong.
He punched the water and bellowed as Phelps swam over to congratulate him.
"He said 'good job, that was a great race'," Schooling said. "I told him to go four more years and he said 'No way.'
"Hopefully he changes his mind. That was fun. I like racing Michael."
Phelps, 31, insists he won't be back for a sixth Olympics. But after winning four golds so far in Rio -- in the 4x100m free and 4x200m free relays, the 200m butterfly and the 200m individual medley -- he'll have a shot at one more -- it would be his 23rd -- on Saturday in the 4x100m medley relay.
Schooling, meanwhile, was absorbing the enormity of his first.
"It hasn't really sunk in yet. I'm full of emotions now," he said. "I don't know what to believe, whether I actually did it or I'm still preparing my race."
Phelps may have been beaten, but the United States raked in plenty of gold on the penultimate night of action at the Olympic Aquatics Center.
Was just a good day says modest Singaporean
When your name is Michael Phelps, it's hard to play second fiddle.
Appearing before journalists after dead-heating for the silver medal in the 100 metres butterfly on Friday, the last individual race of his long career, the most successful Olympian of all time was peppered with questions as gold medallist Joseph Schooling of Singapore sat alongside him.
Gracefully, the American tried to ease out of the spotlight.
"Joe should be getting most of the questions," he eventually told reporters, laughing. "This kid just won a gold medal, guys. Let's ask him some more questions."
When a journalist obliged by asking Schooling how it felt to become "the go-to butterflier in the world right now", the 21-year-old hesitated and glanced to his left at Phelps.
"That's for you bro, don't look at me," Phelps told him.
It was a surreal moment for Schooling, who had just beaten three of the greatest butterfly exponents in Phelps, South Africa's Chad Le Clos and Hungary's Laszlo Cseh, all of whom tied for second.
"That sounds like a lot of pressure. I don't think I'm anywhere close to these three guys next to me," he said modestly in reply to the question.
"Today just happened to be a good day for me.
"I think Chad, Michael and Laszlo should still be the face for butterfly. This is like my first gold medal it's not like I've won 22 or 23."
Phelps shot back: "It's a pretty good one to win, though."
Schooling paid tribute to Phelps as the idol whose inspiration set him on course to become Singapore's first gold medallist in any sport.
"If it wasn't for Michael, I don't think I could have gotten to this point. I wanted to be like him as a kid.
"I wanted to win. And I think a lot of this is because of Michael, he's the reason I wanted to be a better swimmer."
After the medal ceremony, the pair were deep in conversation on the pool deck, and Schooling said he told Phelps the feeling was 'out of this world'.
"He smiled and said, like, I know," Schooling said.
"He's been through it all, and just being beside him, walking beside him and celebrating, I'll really cherish that for the rest of my life."