Doug Kezirian says oddsmakers are confident the Mayweather-McGregor fight will break the boxing record of $50 million in wagers. (2:11)

Multiple $1 million bets on Floyd Mayweather were among a flurry of big money that showed up in Las Vegas on Thursday, shaking up the odds for the undefeated boxing champion's showdown with UFC star Conor McGregor.

The MGM sportsbook took a $1 million bet on Mayweather at -550 odds from a VIP casino guest, who wired in the money to the casino cage ahead of the wager, MGM vice president of race and sports Jay Rood told ESPN. The bet would net just under $182,000, if Mayweather prevails.

Shortly after, William Hill's Nevada sportsbook reported taking a $1.2 million bet on Mayweather at -500 odds from a customer who paid cash. That bet would net $240,000.

After dipping below -500 last weekend, Mayweather's odds were back up to minus-600 at multiple books Thursday.

"The price is skyrocketing right now," Rood told ESPN on Thursday afternoon.

The two $1 million bets are the largest reported wagers on the fight to this point and were part of a surge of action on Mayweather around town Thursday. In addition to the $1 million bets, MGM and William Hill each took $300,000 bets on Mayweather earlier in the day.

The South Point sportsbook reported taking two approximately $200,000 bets on Mayweather within 15 minutes of each other. Those bets followed a $50,000 bet on McGregor at +450 that would net $225,000, if the Irishman pulls off the upset.

While the bigger money begins to appear on Mayweather, the books have a long way to go before evening out the action. William Hill said, even with Thursday's $1.2 million bet on Mayweather, the book still faces a seven-figure liability on McGregor.

For each bet on Mayweather at the Westgate SuperBook, there were 12 on McGregor. But 76 percent of the money was on Mayweather. The average size of a bet on McGregor at the Westgate was $212. The average size of a bet on Mayweather was $8,036.

The betting handle on the fight continues to exceed bookmakers' expectations. By the time the opening bell sounds Saturday night, Mayweather-McGregor is expected to be the most heavily bet boxing match ever, eclipsing the estimated $60 million bet on Mayweather's bout with Manny Pacquiao in May 2015.