LONDON (AP) -- Camille Muffat entered the Olympics with the fastest time in the 400-meter freestyle this year. Somehow, she still managed to fly in under the radar.
This race was supposed to be a duel between defending champion Rebecca Adlington of host Britain and two-time defending world champion Federica Pellegrini of Italy, the world-record holder.
Instead, Muffat led from start to finish Sunday and edged Allison Schmitt of the United States to set an Olympic record.
Inspired by her home fans, Adlington came from behind to finish third for Britain's first medal in the pool, while Pellegrini settled for fifth, then announced she would take a year off after these games and reconsider her future as a swimmer.
"It really hasn't sunk in. I know that I won, which is rare for me at an international meet," Muffat said. "It's one of my first victories, and it's the one that had to be won."
At the 2008 Beijing Games, Muffat was an individual medley swimmer. Over the last couple of years she has changed her focus to the 200 and 400 free. Her coach, Fabrice Pellerin, felt it would be better to focus on a single stroke.
The first signs of Muffat's transformation came when she won bronze in both the 200 and 400 at last year's worlds in Shanghai.
"When I changed from the medley I wasn't sure it was the right move," Muffat said. "Now I know it was a good decision."
At the 2004 Athens Games, Laure Manaudou won the 400 free to become the first French woman with an Olympic swimming title. Manaudou is no longer a leading contender after coming out of retirement, but she is at these games.
"I was happy to see Laure see me win," Muffat said.
Adlington was happy just to get a medal.
"My target has always been the 800," Adlington said. "But I am pleased with that swim. ... Another Olympic medal is just unbelievable. There is not an ounce of disappointment in me."
Adlington trailed for much of the race before pulling into medal contention.
"The crowd definitely lifted me to get that bronze medal," she said.
Pellegrini also still has her best race to swim, the 200 - which she won in Beijing. But she's already made up her mind to take a year away from the sport. She'll be 24 by the time these games end. She's been at the elite level for nearly a decade, having won a silver in Athens at the age of 16.
"Tomorrow I've got the 200, which I won't enter in great spirits," Pellegrini said. "At this point I think I need a year off, then a year from now we'll see if I still have the desire to swim."
The 200 free heats begin Monday and Muffat enters with the second-fastest qualifying time behind Schmitt.
"I'm not going to party, it's just the first day," Muffat said. "But I certainly achieved what I wanted to achieve. It's an Olympic title and that's any athlete's dream."