A gambler in Las Vegas on Friday placed an $880,000 bet on Floyd Mayweather to beat Conor McGregor in their upcoming mega-bout, set for Saturday, August 26 at the city’s new T-Mobile Arena.

The wager was made at odds of -550, meaning a Mayweather win would result in a $160,000 profit for the bettor.

The bet was so large that the original ticket for it (pictured in the tweet below) showed the wrong profit of $120,000, ESPN.com reported. The bookmaking system at the South Point, the casino at which the bet was made, does not allow for total payouts of more than $1 million. A winning bet on this ticket would mean a total payout of $1.04 million ($880,000 wager + $160,000 profit).

So the bet was rewritten as two separate $440,000 bets.

The wager on Mayweather, the largest that’s been made in Vegas on the fight so far, is just what the South Point wanted, since it helps balance the casino’s books. Action on the fight has been overwhelmingly on McGregor, the significant underdog.

William Hill U.S., for example, would love a big bet on Mayweather. At that company, which operates a chain of 108 books in Nevada, 95 percent of the bets on the fight have been on McGregor and 79 percent of the dollars wagered have been on the UFC superstar. Odds at William Hill have shifted from an opening price of Mayweather -1100/McGregor +700 on June 14 to -600/+450 this week.

That drop in Mayweather’s odds goes a long way to explain why the massive bet on him makes sense. Mayweather’s true odds are far greater than -550 – they’ve just been pushed downward by the heavy action on McGregor – so even though the bettor is risking a lot of money to win a relatively small amount, there’s value in the proposition.

The betting pattern on Mayweather-McGregor is not surprising. This is usually how it goes in prize fights: Casual bettors take shots on the underdog, giving them a chance at a big payday for a small investment; professional bettors wait for that action to move the odds on the favorite to a number they see value in and then they come in with big bets.

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