The UFC fighter took a shot at Mayweather's dwindling earnings as he wished the boxer an early happy birthday (Floyd celebrated with a lavish party in Miami this week, despite not turning 44 until Wednesday).
The unbeaten, 50-0 Mayweather once regularly topped the Forbes Forbes World's Highest-Paid Athletes list. That includes 2018, the year after he beat McGregor in his final boxing bout and earned an estimated $280 million to McGregor's $130 million.
But Mayweather hasn't featured in the list since 2019, due to his official retirement and the vast majority of his income being through in-ring activity rather than sponsorships and endorsements.
McGregor jabbed: "Happy birthday Floyd! We miss you on the Forbes" - alongside a photo of the pair staring head-to-head at one another.
'The Notorious' himself was 16th on Forbes World's Highest-Paid Athletes for 2020. Tennis ace Roger Federed topped the standings - just ahead of Cristiano Ronaldo - thanks to Federer's estimated $100 in endorsements.
Mayweather is still said to be worth a massive $560 million (although he does enjoy a lavish lifestyle), while McGregor's net worth is reportedly around $120 Million.
The 32-year-old McGregor is, as an active combat athlete, still earning millions of dollars in the UFC, however. Even after his shock defeat to Dustin Poirier in January, he can expect to earn a hefty payday if the two engage in a trilogy decider later this year.
'Money' Mayweather was originally scheduled to box YouTuber Logan Paul in an exhibition fight this month, but that has been postponed to an as yet unspecified future date.
So no guarantees Mayweather will be returning to the upper end of the Forbes earnings list any time soon.
Perhaps part of McGregor's birthday greeting is a reminder that the last time Mayweather topped this list was when he faced the MMA star in the ring.
And maybe that's exactly what 'Money May' would need to do once more, if he wants to re-join the athletes at the top of the Forbes annual ranking.
Featured image credit: PA Images
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