Few sportsmen can seriously consider themselves the best in the world.
However, when it comes to legends in the making, it doesn't get much bigger than Cristiano Ronaldo and Usain Bolt.
The Jamaican sprinter has secured his place in history with another three gold medals at Rio's Olympics, adding to the trio he won at both the London and Beijing Games.
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And that called for a message of appreciation from one legend to another, CR7 taking to Twitter to congratulate the athlete.
Ronaldo knows what it's like to be the best, but even he hasn't swept away his opponents quite like Bolt has.
The 30-year-old is celebrating his birthday in Brazil on Sunday and will have plenty to smile about as his final Games come to a close.
Reasons to celebrate
Rio has given us plenty of memorable moments, but none more so than Bolt's unbelievable performances.
It goes without saying that even as his Olympic career draws to a close, he will continue to be an inspiration to sportsmen across the field.
In fact, it could all have been so different as he could have had an even closer bond with Ronaldo.
Bolt previously expressed a wish to play for the Real Madrid superstar's former club Manchester United, so they could even have shared a dressing room if things had worked out differently - or if he'd actually been any good at football.
Nonetheless, he clearly belongs on the track, not the pitch, but it's no surprise that he's clearly an inspiration to another of the greatest athletes of our time.
Is Usain Bolt the greatest athlete in the world? Have your say in the comments.