He's won two gold medals in two days at the London Olympics - outgunning US swimming star Ryan Lochte - and is set to take on James "The Missile" Magnussen on Thursday morning. So who is first-time Olympian Yannick Agnel, and how did he come to be called "incredible" by the US's most accomplished swimmer Michael Phelps?
Agnel, 20, was born in the city of Nimes in southern France to a human resources manager and nurse, and was named after tennis player Yannick Noah. He played tennis, judo and football as a child, but, according to reports, turned his focus to swimming as an eight-year-old in 2000 after a neighbour spotted him in a family pool.
When he was 11, his parents divorced. It was a "really tough blow" for the boy, but he said the experience "helped me to grow up, to become more responsible and to be stronger mentally".
Agnel, who describes himself as "quite an introvert", found himself drawn to the isolation that the sport gave him, but also to the thrill of swimming at speed.
"I liked the unique feeling of water sliding over the body. Today, with the speed, I sometimes feel like a speedboat. It's fun, even exhilarating."
Love of learning
Agnel also found himself wanting to lead a life away from swimming outside the pool. A focus on just swimming after his high school graduation was a "bad experience" and he enrolled in the Nice School of Commerce to "rediscover the balance I had in my life as a student and athlete, which is nice".
"It is a different atmosphere and it's necessary to expand your social circle beyond those you spend six to eight hours a day in the pool with. I'm studying oceanography and I like it a lot."
Agnel graduated in 2010, but hit the books again soon after. "I'm glad I got honours - I now have a weight off the shoulders," he said in an interview published on the French Olympic website.
"And I do not stop studying. I am part of a business school in Sophia-Antipolis and I will keep this essential balance between sports and studies.
"I realised that the life of an elite sportsman with nothing else in his life is not the right way for me," he added in another interview. "I have a need to learn beyond swimming and have a curiosity for broadening my horizons."
In between swims, the Frenchman reads works by mid-19th century poet Charles Baudelaire, although French media has quoted his coach Fabrice Pellerin as saying he should "forget about literature, concentrate on swimming".
Trunks, not bodysuits
Following his parents' divorce, Agnel moved to the French Riviera city of Nice, where he met Pellerin, who also trains Olympic gold-medal winner Camille Muffat.
From an early stage, Agnel stood out from his peers - not just for his height - but also for his insistence on wearing simple swimming trunks instead of the now-banned polyurethane bodysuits that were fashionable at that time.
But that decision did not impede his steady rise through the junior ranks of French swimming.
He won eight golds in the 2009 and 2010 European junior championships. In his first international appearance as a senior swimmer, he grabbed the top spot in the 400-metre freestyle at the 2010 European Championships in Budapest, but placed fifth in the 200 free at the world championships in Shanghai.
In March, he set the third-fastest time in the 100-metre freestyle with 48s 02, just behind Australians Magnussen at 47s 10 and James Roberts 47s 63.
But it was his strong anchor swim in the 4x100 metres freestyle relay on Sunday night that saw him power past Ryan Lochte to grab the headlines. Agnel followed that performance with a dominant turn in the 200m freestyle the following day, pipping Lochte again and winning the praise of Phelps - and of the French President Francois Hollande, who pushed past journalists to congratulate him.
"Remarkable," the President said of Agnel, who trains between six and eight hours a day and reportedly sings in the locker room before races to distract his opponents. "It's a big reward for French swimming, a proud moment for him and encouraging for the whole team. He left no doubt."
- FFX Aus