Michael Phelps on Thursday night claimed the 16th Olympic gold medal of his amazing career and 20th in total with a thrilling victory in the 200 metres individual medley.
Phelps led from start to finish and held off fast-finishing American team-mate Ryan Lochte down the final freestyle leg to win in one minute 54.27 seconds, just 0.04secs outside his own Olympic record.
This win comes just 48 hours after he won his 18th and 19th Olympic medals to overtake Russian gymnast Larisa Latynina, who held the previous record with 18.
The win meant the 27-year-old also became the first male swimmer to win the same event at three successive Olympics. He had earlier won the event at the Athens and Beijing Games.
Only two swimmers had ever won the same individual event at three successive Olympics, Australia's Dawn Fraser, in 100 freestyle in 1956, 1960 and 1964, and Hungary's Krisztina Egerszegi in 200 backstroke in 1988, 1992 and 1996.
It is a feat that had eluded generations of the best male swimmers until Phelps, who had the chance of doing it in four different events in London.
Phelps still has the 100 butterfly to come on his programme, with the American the second fastest qualifier into the semi-finals, which will take place later on Thursday.
A tired Lochte, who had been forced to settle for bronze in the 200m backstroke final 30 minutes earlier, took silver in 1:54.90, with Hungary's Laszlo Cseh taking bronze. Britain's James Goddard was seventh in 1:59.05.