A Conor McGregor upset over Floyd Mayweather could cost Las Vegas sportsbooks $40 million

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Floyd Mayweather is no stranger to getting booed.

During the four-day promotional tour he and Conor McGregor took part in to build hype for their upcoming bout, Mayweather was booed relentlessly in Los Angeles, Toronto, Brooklyn, and London, while crowds cheered an emboldened McGregor as he prepared for his first professional boxing match.

It will likely be more of the same with the crowd in Las Vegas on Saturday, but Mayweather can rest assured knowing that there will be at least one group pulling for him to get the win: Las Vegas bookmakers.

Currently, Mayweather is a -550 favorite to beat McGregor at the Westgate Las Vegas SuperBook, and most everyone in the fighting world agrees that he's a safe bet to win the fight. Unfortunately, that also means that bettors have to put down $550 just to win $100 if Mayweather's hand is raised at the end of the night.

For boxing and gambling experts, these are still great odds — during a recent appearance on Cousin Sal's "Against All Odds" podcast, ESPN boxing analyst Max Kellerman said "Mayweather would literally be a tremendous value at 50-to-1."

But for casual gamblers, those odds are a big ask, and right now, they can't get enough money on Mayweather.

Imagine you're in Vegas for the fight weekend and you know you want to bet something on the fight — just to get a bit of action in on the event that everyone in town will be talking about. You go to the betting window and ask to put $100 on Mayweather, only to find that you'd only win $18 for your bet. So instead you put your money on McGregor, who at +400 odds, can win you $400 for your initial investment.

This scenario is happening over and over in Las Vegas, to a point that sportsbooks have had to keep Mayweather's odds ludicrously low in order to attract more money in order to cover the onslaught of McGregor action from casual bettors.

According to Jay Kornegay, VP of Race and Sports Operations at the Westgate Las Vegas SuperBook, McGregor is currently getting 95% of the betting tickets, meaning that if he pulls off the upset, 19 out of every 20 bets they have taken would be winners for the bettor and losers for the book.

Despite McGregor's heavy lead in ticket count, 80% of the money on the fight is still on Mayweather, thanks to a few big bets by both professional bettors and people with the money who know a good investment when they see it. As the weekend approaches and more high rollers come to town for the fight, there's a small chance that a slew of five- and six-figure Mayweather bets swings the sportsbooks' interests, but at the moment, the casinos are in a position to be pulling hard for the favorite.

Adding to casinos liability is the fact that this fight opened at much longer odds — Westgate LV opened in February with McGregor as a +1100 underdog, meaning that people that backed the Irishmen early would cost casinos nearly three times as much should he pull off the upset.

With a bit of back-of-the-envelope math applying the current odds and money split to the actual fight, if the total handle for all the casinos in Las Vegas for the fight is $60 million, as Director of Race and Sports for Boyd Gaming Bob Scucci recently estimated on ESPN's Behind the Bets podcast, Las Vegas sportsbooks will owe Mayweather bettors roughly $8.7 million when they hand in their winning tickets after the fight, but will be on the hook for $48 million should McGregor prevail.

While these are all based on estimates and the odds vary from book to book, it's safe to say that Mayweather's biggest fans in Las Vegas this weekend will be the casinos. 

"Ultimately, we want to be in a position where we win a significant amount on Mayweather, but we don't want to be destroyed if McGregor wins," John Murray, a manager and oddsmaker at the Westgate LV Superbook, told ESPN's Doug Kezirian. "We don't want this fight to cost us our whole year."

When millions tune into Saturday's $99.95 pay-per-view, you can be sure that bookmakers all across Vegas will be watching closely.

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