The list of the most heavily bet-upon sporting events in this city's history is a top 20 exclusively of Super Bowls.
Until this weekend.
Fight fans have been debating for years over who's the better fighter, and they finally have an opportunity to be financially rewarded.
"America has to bet this fight," veteran sports book director Jay Kornegay of the Westgate Las Vegas Superbook said. "Everyone coming to this town, they're going to wager on this fight. And we think 70% of the action will come in from Thursday on."
Kornegay said some of his peers think the welterweight title unification bout between boxing's top two pound-for-pound fighters will eclipse the record $119 million bet in Nevada for the 2014 Super Bowl pitting the Seattle Seahawks against the Denver Broncos.
Kornegay and MGM Resorts' race book director Jay Rood are more cautious, estimating the Mayweather-Pacquiao wager total will be around $80 million.
Yet, Rood said already brisk betting will erupt in the next few days when the army of fight fans begin arriving en masse to watch the Mayweather (47-0) fight the record eight-division world champion Pacquiao.
Not only has the 16,800-seat MGM Grand Garden Arena sold out, generating a record $74 million live gate, with many of the tickets scalped at 10 times higher than face value, 50,000 closed-circuit seats have been sold at all the MGM properties in town and hotel rooms are scarce.
The traffic at the Las Vegas sports books is expected to be so heavy that Rood has positioned as many as 50 other MGM employees, including ushers and box-office workers, to write betting tickets at the windows.
"It's going to be an all-day event for us, and when you throw in the Kentucky Derby on top, the money from now on will be coming in steadily," Rood said.
MGM Resorts has Mayweather listed as a minus-200 favorite, meaning you need to bet $200 to win $100, with Pacquiao a plus-170 underdog, or a bet of $100 to win $170. At Westgate, the odds are Mayweather minus-250 and Pacquiao plus-185.
The volume of bettors encouraged Rood and Kornegay to also create proposition bets, such as the total of judges' scores for each fighter if the bout goes the full 12 rounds. For Mayweather, the over-under is 347 1/2, and it's 336 1/2 for Pacquiao.
At Westgate, the odds that the fight will last 11 full rounds is minus-300. Pacquiao has 38 knockouts, but hasn't stopped anyone since Miguel Cotto in 2009, and Mayweather's last knockout was a surprise punch that dropped Victor Ortiz in 2011. Mayweather actually has similar odds of winning by knockout (9-2) as Pacquiao (4-1).
Longshot bets are available, too, like the 45-1 odds of Pacquiao winning by first-round knockout.
Kornegay said betting patterns are typical, with 87% of bets so far on the underdog Pacquiao.
"Most people would rather bet $20 and win $40, than bet $20 and win $10," Kornegay said. "We see it at the window: 'Yeah, I'll bet Mayweather,' then they see it's $21.50 to win $10, and they're like, 'Oh, what about Pacquiao?' "
However, three bettors have placed six-figure bets on Mayweather at Westgate, one investing $500,000. Kornegay said high rollers traveling to Las Vegas often wire-transfer their money to the casino.
"If the fight were tonight, we'd probably need Pacquiao [to win], but I expect the liability will be reduced every day, to the point that by fight night, we may need Mayweather," Kornegay said.
Rood likes the bet of Mayweather winning by decision.
"Forty-seven-and-oh is a pretty good rate of return," Rood said. "A decision looks like the way to go, and the defensive fighter usually prevails."
At the MGM Grand book, bettors Ron Knight of Los Angeles and Antyon Brown of El Paso plotted bets based on the theory that a rematch is inevitable.
"They're going to double-dip," Brown said.
Many agree, as odds for the Mayweather-Pacquiao fight ending in a draw have shrunk drastically, from an opening line of 22-1 to 6-1.
"There's going to be controversy, decision or draw, with the mind-set of the rematch, because after this, boxing is over," Knight said. "It needs something to be talked about, something that'll make people put forth their money to want to do it again. Both of them are at the end of their careers, this is the most astronomical payout in forever, so why not do it again?"
Both fighters are popular with gamblers.
Mayweather is usually a heavier favorite, and Pacquiao hasn't been an underdog in a fight since retiring
"I've bet against Mayweather many times," Kornegay said. "After one round, you're [often] saying, 'This guy's way too slow, he's not going to be able to touch him.' Pacquiao's a terrific fighter, though, and it's boxing, so anything can happen."