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The sun is setting and rising at the same time on United States swimming.

On the same night Michael Phelps won his last individual race, giving us a final glimpse of another big kick for his 17th gold medal, he shared the spotlight with a pair of teenagers who also stood atop the medal podium as Olympic champions.

It wasn't Missy Franklin's first time. She's matched expectations here with multiple wins. But Katie Ledecky, not yet driving age, had never seen such a stage.

Some helpful words from Phelps, the winningest Olympian of all time, helped the 15-year-old get through it all.

"Michael is the first Olympian I ever met when I was six, right before I started swimming. So to hear a good luck from him before the race was really cool," said Ledecky. "I just thought back to that and it really calmed me down."

Phelps surged to win the 100-meter butterfly Friday night, coming back from seventh place at the turn to beat the swimmer who'd out-touched him three nights before in his signature race.

Kicking into gear over the last 50 meters, Phelps touched in 51.21 seconds -- .23 ticks ahead of South Africa's Chad lo Clos, the 200 fly champ, and Russian Evgeny Korotyshkin, who shared the silver.

It was a rout compared to Phelps' last two 100 fly wins at the Olympics: .04 seconds over teammate Ian Crocker in Athens and, famously, .01 seconds over Milorad Cavic in Beijing.

It was his 21st Olympic medal and 17th gold, extending both records. He will swim once more here, in the 400-meter medley relay, which the U.S. is favored to win.

Then, Phelps will hang up his goggles after what he swears is his last Summer Games.

"I thought it would hit me harder than what it is right now. A lot of those emotions haven't really come through my brain in the last week," said Phelps. "Once I'm done, there's going to be a lot more emotion. I'm kind of in a meet mode. You have 15 or 16 sessions, you start and then you finish and then it's over."

Things are just starting for Franklin and Ledecky.

Franklin, the bubbly 17-year-old who trains in Aurora, Colo., site of the fatal movie theater shooting last month, smashed a world record to win the 200-meter backstroke for her third gold medal in London.

Her time of 2:04.06 seconds broke Kirsty Coventry's world mark from 2009 by .75 seconds. Franklin, who also won gold in the 100 back, has four medals overall here. Russia's Anastasia Zueva was second and Elizabeth Beisel of the U.S. took bronze.

"It feels amazing, it's my favorite [medal]. I can't think of a better way to end," said Franklin. "I knew I was going to take it out and have fun and that is what I did. I am the happiest girl alive. ... It was an incredible field I was up against. On my way home, the last 25 (meters), I know I was giving it everything. I could not feel my arms and legs."

Franklin should go in the women's medley relay Saturday and become the first female U.S. swimmer to race seven events at the same Olympics.

Ledecky swam most of the 800-meter freestyle under world record time, blowing away seven other swimmers to win her first Olympic final. She led for good after the first 150 meters and touched in 8:14.63 -- 4.13 ticks ahead of Spain's Mireia Belmonte Garcia.

Great Britain's Rebecca Adlington, the world record holder and 2008 gold medalist, ended 5.69 seconds back. Ledecky was ahead of Adlington's record time of 8:14.10 until the last 50 meters. She finished just .53 off it.

Later, her lips quivered and she cried during an emotional medal ceremony as the U.S. anthem played for the third time Friday night.

"I figured I was going pretty fast," said Ledecky. "At one point I thought, if I'm gonna be close to this record I don't even care. I just want to get my hand on the wall first."

Ledecky broke the American record in the women's 800 set by Janet Evans in 1989 by almost two seconds. Evans tweeted her congratulations to the young swimmer.

"Congrats to #katieledecky on her gold medal in tonight's 800 free," Evans wrote. "Amazing swim, so proud of her for bringing distance gold back to the US!"

Though Phelps shared the focus with U.S. teammate and rival Ryan Lochte coming into these Olympics, he will walk away with more wins.

Phelps and Lochte split their head-to-head races, but Phelps has more golds (3) than his teammate (2) going into the last day of swimming.

Phelps also became the first male swimmer to win the same Olympic event three straight times -- and he's done it two times over. It happened first against Lochte in the 200 IM on Thursday night. He has now also won he 100 fly three straight times as well.

"My start of the meet wasn't what we wanted, but I seemed to pick up some steam at the end of the meet, and was able to finish with two individual golds," said Phelps. "To be able to finish that way, you can't really finish any better. I'm very pleased with how everything went."

The U.S. has 28 swimming medals at the London Games, well more than half its total haul so far and more medals in one sport than any country has overall except China.

Also Friday night, France's Florent Manaudou won the 50-meter free, the first swimmer from his country to capture gold in the shortest Olympic sprint event.

Manaudou touched in 21.34 seconds -- .20 seconds ahead of American Cullen Jones. World record holder and 2008 Olympic champion Cesar Cielo, who beat Frenchmen Amaury Leveaux and Alain Bernard in Beijing, came in third for the bronze.

Former Olympic champion Anthony Ervin of the U.S. finished fifth in his return to the games. Ervin won the race at Sydney in 2000, then later sold his gold medal to aid victims of the Indian Ocean Tsunami. He came out of retirement after nine years to give the Olympics another try.