Michael Phelps showed no signs of complacency on the eve of his retirement and provided an unforgettable reminder of his talent and unquenchable determination to win by snatching the 100 metres butterfly gold.
The American, whose list of achievements in the Olympic pool is already beyond comparison, came from seventh place at the turn to overpower his rivals and win his 17th gold medal.
His victory capped an extraordinary night of swimming at London's Aquatic Centre.
Missy Franklin broke the world record in the 200 backstroke and her 15-year-old team mate Katie Ledecky pulled off a stunning upset in the 800 freestyle.
Only Frenchman Florent Manaudou, the younger brother of Laure Manaudou, prevented an American sweep of the four golds on offer when he won the 50 freestyle sprint to join his famous sister as an Olympic champion.
Phelps and Franklin became the first triple gold medallists of the London Games and the pair look certain to win one more each in Saturday's medley relays.
Phelps won the 100 butterfly gold at the last two Olympics but his chances of making it three in a row looked slim when he turned for home and all but one of his opponents were ahead of him.
But once he started to roll over his giant shoulders and kick his powerful feet as fast and hard as he could, he quickly caught up and powered past them all to win in a time of 51.21 seconds.
South Africa's Chad le Clos, who beat Phelps in the 200 butterfly final, dead-heated for second with Russia's Evgeny Korotyshkin but neither man could hold off Phelps, who now has a total of 21 Olympic medals.
"This is my last individual event. It was awesome," Phelps said. "This swim was pretty important to me. I wanted to win."
Franklin, competing in her first Olympics, confirmed her arrival as the new queen of the pool when she blew away her opponents, finishing well clear of Russia's Anastasia Zueva, who won the silver medal, and America's Elizabeth Beisel, who collected bronze.
Franklin, who also won gold in the 100 backstroke and 4x200 freestyle relay, finished in 2:04.06, slashing three-quarters of a second off Kirsty Coventry's world record, the seventh time a mark set when polyurethane was the suit du jour has been broken in as many days in the London Olympic pool.
"I knew I was going to take it out and have fun and that is what I did," she said. "I am the happiest girl alive."
The 15-year-old Ledecky, the youngest member of the entire 530-strong US Olympic team, came agonisingly close to setting an eighth world record when she won the 800 freestyle final, the longest women's event in the pool.
The teenager sliced more than five seconds off her best time just to qualify for the team at the US trials earlier this month then hacked off another five seconds on Friday to win the Olympic title.
"Michael and Missy's races really got me pumped," said Ledecky, who was under world record pace at every turn and only missed it at the end by less than a second.
"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."
Ledecky's win ruined Rebecca Adlington's hopes of providing Britain with their first gold medal in swimming at the Games.
The Beijing champion tried to keep up with her younger opponent but faded to finish third as Spain's Mireia Belmonte Garcia got past her to grab her second silver medal of the Games.
"I do not know whether the expectations and environment got the better of me," Adlington said.
"I gave it all and I hope that people at home see that."
The 21-year-old Manaudou charged down the pool to get his hand on the wall first and win the frantic one-lap dash in a time of 21.34, ahead of American Cullen Jones and Brazil's Cesar Cielo, the Beijing gold medallist.
His sister Laure won the 400 freestyle gold at Athens in 2004, becoming the first female French swimmer to win an Olympic title.
Now the family has a second gold and France have four in swimming in London, level with China, and trailing only the US who have amassed 14.