Monaco - Michael Phelps has credited losing to Chad le Clos in 2012 as the main reason for his comeback to swimming.
Phelps, the most decorated Olympian of all time, had retired from professional swimming after the 2012 London Olympics.
It was then, of course, that Le Clos stunned Phelps and the world by winning gold in the 200m butterfly.
That moment was one that South Africans will never forget, but it never sat well with Phelps and was ultimately the reason that he decided to return to the sport in 2014.
It was a decision that he would not regret.
Phelps won five gold medals and a silver at Rio 2016 and he also won back his 200m crown from Le Clos, who did not medal in the race.
It took Phelps' tally to 28 Olympic medals - 23 of them gold.
Now retired for good, Phelps received one more honour when he was given the Comeback of the Year award at the Laureus World Sports Awards in Monaco on Tuesday night.
"I think about that a lot," Phelps told Sport24 when asked what role losing to Le Clos had played in his comeback.
"If I win the 200m 'fly in London I probably don't come back."
Phelps said that he wasn't even sure he was going to swim the 200m in Rio - that decision coming late on in his Olympic preparation.
"I had to dig deep," he said.
"I don't think I ever had to dig that deep in a race in my career and that is something I was proud to have back after the loss in 2012.
"I can now look back on my career and say that the 200m 'fly in Rio was probably the greatest race of my career."
The Le Clos v Phelps rivalry may have ended with the American on top. but Phelps did have a few kind words for a man who he hasn't always seen eye to eye with.
"I am excited to see what Chad does over the next four years," he said.