Not bad for a 20-year-old at his first Olympics.
Agnel led the 200 freestyle from start to finish Monday and clocked 1 minute, 43.14 seconds for the best time ever in a textile suit—a whopping 0.72 ahead of Michael Phelps' 2007 mark.
"I had to look twice at the scoreboard to be sure it was the right time. I had a race plan in my head, but this is above my expectations and hopes," Agnel said. "I worked on keeping my speed and putting all my guts into the last 50. I don't know what to say—it worked."
French President Francois Hollande, who was on hand for the race, put it more simply: "Remarkable—two gold medals two nights in a row."
Hollande pushed his way past reporters to congratulate Agnel.
"It's a big reward for French swimming, a proud moment for him and encouraging for the whole Olympic team," Hollande said.
Defending silver medalist Park Tae-hwan of South Korea and 400 free champion Sun Yang of China shared silver in 1:44.93, while world champion Ryan Lochte finished fourth and world-record holder Paul Biedermann of Germany was fifth.
With so many standouts, and despite Phelps' decision not to enter, the event was dubbed the "Race of the Century."
On Sunday, Agnel anchored the French victory in the 4x100 freestyle relay, using his 6-foot-6 (1.98-meter) frame to push ahead of Lochte and the Americans.
"He's a great racer, there's no doubt about it," Lochte said. "He's quick and he showed it last night and tonight."
He shot to prominence at the senior level two years ago with his victory in the 400 free at the 2010 European Championships in Budapest, although he struggled at last year's worlds in Shanghai with a fifth-place result in the 200.
Agnel won eight golds at the 2009 and 2010 European junior championships and he is competing in his first Olympics.
Named after French tennis great Yannick Noah, Agnel played tennis before he discovered swimming at the age of 8 in his neighbor's pool in the southern town of Nimes. His parents split when he was 11 and Agnel met his coach Fabrice Pellerin after moving to Nice.
"My parents' divorce was really a tough blow," said the shy swimmer. "But it helped me to grow up, to become more responsible and to be stronger mentally."
On Sunday, Camille Muffat gave France another gold in the women's 400 free, and the country stands second to the United States in the swimming medals table.
It's been a pleasant surprise for a team undergoing a generational change, with defending 100 free champion Alain Bernard qualifying only for a morning heat in the relay and Fred Bousquet, another sprinting standout, failing to make the team altogether.
Agnel's next event comes Tuesday morning with the 100 free heats. He's also swimming the 4x200 free relay and the 4x100 medley relay.
"That's going to be complicated," Agnel said of the 100.
The favorites for the 100 are James "The Missile" Magnussen and James "The Rocket" Roberts of Australia plus Cesar Cielo of Brazil, but at this point nobody's counting out Agnel for the sport's signature event.
"As they say in English, 'It's giving me positive vibes,'" Agnel said. "We're on track. We'll approach it without pressure, and with a lot of pleasure and fun, which we've been doing since the start of the week."
AP Sports Writer Samuel Petrequin contributed to this report.