Michael Phelps won his first individual gold at London 2012 - and his 20th Olympic medal - by beating Ryan Lochte in the men's 200m individual medley.
American Phelps, 27, led from the front and looked as if he might break the world record.
He missed out but claimed a 16th gold medal, becoming the first man to defend an Olympic swimming title twice, having won this event in Athens and Beijing.
"Extraordinary. He is the first man in the world to successfully defend his Olympic title twice. Three consecutive golds in this event is incredible. I'm glad he's swam well and now he can relax a bit."
Hungary's Laszlo Cseh was third, while Britain's James Goddard was seventh.
"Somebody told me that, with 25m left, I was under world record pace, so it's a little frustrating not to get that," said Phelps, who finished in 1:54.27 - 0.27 shy of the mark held by countryman Lochte.
"But to win a gold medal and be the first to three successive titles is something pretty special and something I'm pretty happy for."
Lochte, 27, had entered the men's 200m backstroke final earlier in the evening and looked a little jaded in his second race of the night. But his silver means he has now won two golds and five medals in all at London 2012.
Phelps has won two golds and two silvers at the Aquatics Centre,
having already overtaken former gymnast Larissa Latynina
as the Olympian with the most medals. Latynina won 18 medals between 1956 and 1964, while Phelps arrived in London with 16.
"The President of the United States Barack Obama called me on Wednesday," Phelps told BBC Sport. "It was pretty cool.
"Someone called me up and asked me to hold on as they had the president waiting to speak to me. He told me that everyone is supporting me. It was very special and he said to say 'hi' to my mum."
Goddard clocked a time of 1:59.05 and said: "I tried to go for it and paid for it down the back, but it's a been a fantastic experience."