A reinvigorated Michael Phelps, the most successful Olympian of all time, showed the pretender to his crown Chad Le Clos how it's done as he took gold in his last individual race.
Three days previously, South Africa's Le Clos had astonished the Aquatics Centre by beating his hero Phelps into second place in the 200 metre butterfly, and it looked like Phelps' reign was already over.
But Phelps, riding high on a gold medal from yesterday, reminded the world this morning of his incredible talent and determination as he came back from seventh at the halfway point to take gold in the 100m butterfly, 0.23 seconds ahead of Le Clos.
If it rankled, the amiable Le Clos showed no sign. For him, it was an honour just to be there.
"When I was racing I was racing for the gold but I'm just thankful that I had the opportunity to race another Olympics final and live my dream of racing with Michael," he said to reporters.
"But he got me this time."
Phelps has repeatedly praised first-time Olympian Le Clos, his competitiveness and his ability to swim multiple events and distances.
"It's going to be fun to watch Chad and see what he does over the next couple of years," he said.
Maybe they would go cage diving together in South Africa, Phelps said, the wry smile and disappointment of earlier in the week replaced with good humour and obvious enjoyment of the moment.
Phelps now has 21 Olympic medals, including 17 golds.
But the record breaking swimmer got off to a slow start in London and has struggled to reach the dizzying heights of his Beijing success, when he won eight golds and seemed unstoppable.
Evidence that all was not well at the top came on the first night of the 2012 swimming programme, when Phelps only just scraped into the final and then, to astonished gasps from the crowd, wound up out of the medals in the 400 individual medley, an event he had won in Beijing and Athens.
On Sunday, he suffered his second defeat in as many days when France beat the U.S. for gold in the 4x100 freestyle relay, while Tuesday saw Phelps throwing his goggles down in frustration when he was pipped to the post by Le Clos in his favourite event, the 200 butterfly.
But the tide started to turn as he won relay gold and then beat U.S. rival Ryan Lochte to take gold in the 200 medley earlier this week.
He is also almost guaranteed one last gold and chance to stand on the podium tomorrow night, when the U.S. relay team swim in the 4 x 100 metre medley, an event in which they have never been beaten.
This means he will likely leave London with four golds and two silvers from seven events - not quite Beijing, but not a bad example to set young hopefuls.
"We can smile and be happy," Phelps said. "It was fun."