Anthony Ervin has made history to become the oldest ever Olympic swimming champion following a stunning victory in the 50m freestyle.
The 35-year-old American, who won joint gold in the same event in 2000, out-touched France's Florent Manadou by .01 seconds in a thrilling finish.
Ervin also won gold when he was 19 but quit the sport just four years later.
After giving up swimming, Ervin suffered with depression but turned his life around and returned to the pool.
Now Ervin, the second-oldest swimmer in Rio, has capped an amazing return to the top.
After returning to competition in 2011, he qualified for the USA's Olympic team for the London 2012 and came fifth.
He won the first Jewish gold medal as part of the team that won gold in Monday's 100m freestyle relay and now is an outright Olympic champion for the first time following a shock win.
He said: "I kind of laughed. It's surreal, almost absurd I was able to do it again.
"I just feel the overwhelming support of all of my people. I won that for my team, my country and my people.
Having sold his 2000 gold medal on Ebay to raise funds raise money for victims of the 2004 tsunami.
He indicated he would keep this medal "for now", adding: "Who knows what the future holds?
"But maybe a piece of me really wanted to see if I could get that medal back - make it a little bit harder on myself. I got it."
Ervin, who hasn't ruled out competing again in four years' time, Ervin revealed he became a father during the US trials last month but has yet to see his newborn daughter.
He said he wanted to be at the birth but was still competing and then got caught up in Olympic preparations.
"Oh man, it's like a thunderbolt," he said. "I haven't had a chance to meet her yet and I tried to send a message to her after my race."
Multiple gold medallist Katie Ledecky, 19, was among those in awe of Ervin's feat and: "Wow, who does that, winning 16 years apart?"
Ledecky had earlier clinched her fourth goal medal of the Games.
The teenager took nearly two seconds off her own world record to win in eight minutes 4.79 seconds, nearly 12 seconds clear of the rest.
Ledecky's dominant display rounded off a stunning debut Olympics with a world record nearly 14 seconds faster than what it stood at when Rebecca Adlington set it at the Beijing Olympics.
"I had a lot of fun tonight," Ledecky said. "I just wanted to push myself and see what I could do."