Michael Phelps claimed his 20th Olympic gold with a dominant victory in the 200 metres butterfly in Rio beating rival Chad Le Clos for the top spot.
Phelps doesn't often lose in the Olympics but four years ago, the American swimmer had to settle for a silver in the 200m butterfly at the London Olympics, when his South African competitor beat him to the wall by 0.05 seconds.
The defeat was a big blow to Phelps who considers the 200m butterfly his signature event.
But four years later, the American swimmer finally got his shot at revenge and photographers were on hand to catch that exact moment Le Clos realised his gold glory was over - with about 10 metres to go.
Le Clos finished in fourth place.
Here's the South African swimmer congratulating his competitor for winning gold:
Only hours earlier, Phelps was caught on camera giving Le Clos a less than impressed look (also known as the #PhelpsFace) as they were psyching themselves up for the butterfly semi-final.
But before they became rivals, the swimmers used to be friends, especially after Phelps retired in 2012.
But in 2014, Phelps had a change of heart and decided to compete in the 200m butterfly, specifically because he thought the field was slow and he had a chance to win gold.
You can guess how Le Clos responded to that.
After winning at the at the 2015 World Championships, the South African told NBC Sports: "He's been talking a lot of smack in the media about how slow the butterfly is, so I just can't wait until I race him."
Phelps later responded saying he was motivated to perform better by the comments.
"The comments were interesting," Phelps told the Baltimore Sun. "It just fuels me. If you want to do it, go for it. I welcome it."
Their rivalry has also kept the internet very busy:
Although Le Clos fans aren't happy with the swimmer being trolled on Twitter:
Well, there's still the 100m butterfly to go and anything can happen.