By any measure, Conor McGregor enters his Aug. 26 boxing match against Floyd Mayweather Jr. as a massive underdog.
As of this writing, Mayweather is a -500 favorite to McGregor’s +375 (bet $500 to win $100 or bet $100 to win $375), but the line hardly reflects the actual odds at OddsShark. Oddsmakers opened Mayweather as a -2500 favorite; McGregor was a +1100 underdog.
But a historic level of wagering on McGregor has driven the price so low as to be almost unbelievable, especially if you consider Mayweather is a virtual lock.
Mayweather’s average line over the past decade is roughly -600. That’s the same as the current line against McGregor, of course, but you must remember that Mayweather averaged -600 while facing world-class boxers like Oscar De La Hoya, Canelo Alvarez and Manny Pacquiao.
Those boxers had long and storied careers before they stepped in the ring with Mayweather; McGregor has zero professional or amateur boxing bouts.
Make no mistake: This is one of the most lopsided fights in combat sports history. Even with the standard boxing practice of feeding cans to top prospects to build up their names, the idea of an undefeated, legendary boxer facing a debutant is unheard of.
In fact, if not for the greed of the Nevada State Athletic Commission—and its unique trait of bending over backward for Mayweather no matter the circumstance—this fight would not even be sanctioned. It’s only happening because it’s big money, and Nevada never turns down big money.
We’ve established that Mayweather vs. McGregor is a historically lopsided fight. What if McGregor wins? It would be the biggest upset in combat sports history, without question.
With that in mind, let’s take a walk through the history books and look at some of the other biggest upsets in both boxing and MMA history.