(This is the second installment of a three-part series on the gambling aspect of the “The Money Fight” between boxer Floyd Mayweather and UFC champ Conor McGregor. Check out Part 1.)

If Conor McGregor, a man who despite a championship MMA career, has never been paid to put on boxing gloves, somehow manages to beat undefeated, five-division boxing world champ Floyd Mayweather at his own game on Aug. 26, it will go down as one of the greatest upsets in sports history.

But in that instance, believe it or not, Mayweather (49-0 boxing) might not be the biggest loser. After all, the 40-year-old retired pug will have a possible $300-million-plus purse to assuage any humiliation. And of course underdog fish-out-of-octagon McGregor really has nothing to lose (and a reported $100-million-plus to gain). The people who might be sweating the outcome of “The Money Fight” from a financial standpoint are those who ply their trade in a different kind of cage – that of the Vegas sportsbook cashier.

A contest between mismatched opponents can be a dream for bettors, either looking to score a little scratch on a sure thing, or drop a pittance with long hopes of scoring big on an upset. But those same conditions make lopsided fights an uneasy proposition for sportsbooks. Bookmakers want to accurately handicap the event, but if they lay odds that favor a competitor too much, all the action will go to the underdog. And if that dog then shocks the world, the house might not have enough money to cover its losses.

Twenty years ago when unknown James “Buster” Douglas upended the boxing world by knocking out then-undefeated Mike Tyson, no bettors got rich – because almost no bookmakers had taken bets on the seeming farce.

Douglas was a 42-1 underdog in that 1990 fight. Today, the odds against McGregor are only around 5 to 1. Still, sportsbooks and bettors are watching the lines closely.

“In terms of true odds, Mayweather should be a much greater favorite,” Todd Fuhrman, gaming insider for Fox Sports and CBS, told MMAjunkie. “But sportsbooks can only incur so much liability. As is, books in Vegas are facing a high-six-figure, low-seven-figure liability if McGregor pulls it out. If he does pull off the unthinkable, you’ll hear a lot of sportsbooks crying about how they’re going to pay the power bill on Aug. 27.”

Jay Rood, vice president of race and sports at MGM Resorts, is trying to make sure that doesn’t happen. He and his fellow Vegas bookmakers have been extra conservative, Rood even already having dropped Mayweather from a $7 opening bet to $4.50.

“This is the biggest liability we’ve faced on a boxing match in six or seven years – and we’re still a month away,” said Rood.

As of late July, McGregor was still outpacing Mayweather on volume in the MGM books, the Irishman drawing around 3,000 wagers to the boxer’s 70. But Rood said the amount of money was still fairly close. Even though Mayweather’s odds aren’t attractive to a large number of casual bettors, no one was risking big money on a McGregor upset.

Meanwhile, for seasoned gamblers, betting big on Mayweather seems like a pretty solid business proposition.

“This will be the biggest bet I’ve ever made in my life. I’m going to go out and bet this fight because it’s stealing money,” said Anthony Albanese, odds consultant for Diamond Sportsbook, an offshore betting service that as of late July, had McGregor at +675. “I think that’s insane. If you lay 675 (on Mayweather) right now you’re stealing. I think you’re printing money laying at that price.”

With far less overhead, less-strict government regulation, and a desire to draw bigger players, offshore sites like Diamond Sportsbook can be a little more adventuresome with their odds. When the fight was first announced, there was stark disparity between Vegas’ numbers and those of the offshore sites, but that gap has narrowed as all odds makers try to find their level of comfort. Of course, lines will move with every circus-sideshow press conference and particularly in the days and hours leading up to the actual Aug. 26, which airs on pay-per-view (for $100) from T-Mobile Arena in Las Vegas. Albanese said even time-zone difference may come into play, with a flurry of activity coming from McGregor’s native Ireland and Europe spurring a North American response later in the day.

“We’ll let it unfold and see where we find ourselves,” MGM’s Rood said. “If we see zero support for Mayweather, you might see the numbers really drop before the fight starts, with some unbelievable deals relative to opening odds—a guaranteed win with relatively zero risk.”

Rood said he’s not worried about his own risk and that of the book. He said he’s “fairly confident” he’ll see the balance he needs in wagers to offset the liability. In his business, it’s never a good idea to overreact.

“As long as this fight goes off without some sort of incident and there’s a good honest effort by both fighters, the crowd feels they got their money’s worth, and fans have legitimate opportunity to cash their ticket, it’ll be good for everybody,” Rood said.

For more on “The Money Fight: Floyd Mayweather vs. Conor McGregor,” check out the MMA Rumors section of the site.

Tony Rehagen is a freelance writer based in St. Louis. His work has appeared in Men’s Health, GQ, espnW and others. Follow him on Twitter @trehagen.