Michael Phelps grabbed another big slice of sporting immortality as he became the first male swimmer to win the same individual event at three Olympics with victory in the 200m medley.
Ryan Lochte had predicted the London Games were his time, but Phelps showed on Thursday it was still his.
With his mother Debbie yelling "Go, go, go" from the stands, he forced his American teammate to settle for silver as led all the way and touched in one minute, 54.27 seconds, just off his winning time in Beijing but still good enough for gold.
It extended his records for most Olympic medals - now 20 - and most gold medals - 16.
The gold came just 48 hours after he won his 18th and 19th medals to become the most decorated Olympian in history, overtaking Russian gymnast Larisa Latynina who won 18.
And that's not the end of it for Phelps at his farewell Games.
After a slow start, he's now won two golds and two silvers in five races and still has two more events to go.
Phelps acknowledged he set out to take advantage of the fact Lochte had raced just half an hour earlier, fading to third in the 200 backstroke final behind fellow American Tyler Clary.
"I knew it would be tough for him having the backstroke final before," said Phelps.
"I wanted to kind of push the first 100 as much as I could just to see what happened."
The victory saw Phelps overturn the result of the 400m medley, where he lost to his friend Lochte.
He described his milestone feat of winning the 200 medley gold in Athens, Beijing and London as "something very special".
The victory saw Phelps overturn the result of the 400m medley.
Phelps, who will retire after the Games, said: "Going into every (pre-race) call room, I am saying this is my last semi, or my last fly, so we are chalking up all the 'lasts' for certain things.
"I said to Ryan this was our last 200 of the meet and our last 200 together, we were just joking around about it. Ryan has been one of the toughest all-around competitors I have ever swum against."
Phelps could also win the 100m butterfly title for the third time in succession after later returning to the pool to win his semi-final in 50.86 and advance to the final as fastest qualifier.
"Tonight was a tough turn around, but I am very pleased to go 50.8," said the 27-year-old.
"It was my fastest time this year and the final is going to be a good one tomorrow. Hopefully, I can be not a body length behind after the first 50m."
Lochte, who can still celebrate his 28th birthday on Friday with a fifth medal of the Games, said: "It's not the colour medal I wanted but I can't complain. I've had some ups and downs but I'll take it. I had 15 minutes between swims and I was really happy they let me cool down in the diving pool."