The fact that Floyd Mayweather plans to bet on himself to beat Conor McGregor in their Aug. 26 boxing match shouldn’t come as much of a surprise. Mayweather likes to bet large sums on sporting events. And not only is he betting on himself, but he told Jimmy Kimmel on Tuesday night that he would repay Kimmel should his bet on Mayweather be a loser.

(McGregor also allegedly is betting on himself, if you believe the Irish Sun.)

What’s a little surprising is that he’s allowed to do so in the first place, unlike in other sports. Gambling barely comes up in the Nevada Athletic Commission’s rules and regulations, which prohibit match-fixing and bets made through illegal bookmaking. But sports gambling is legal in Las Vegas, where the bout will take place, so nothing is stopping Mayweather from betting on himself.

Whether Mayweather should bet on himself is another matter. While still in his role as the Ethicist for the New York Times Sunday magazine, Chuck Klosterman wrote in 2014 that it’s okay to bet on yourself if you do it all the time, wagering the same amount through legal channels each time. Otherwise:

If an athlete bets on himself only periodically — or even if he bets varying amounts, depending on the opponent — he is opening a window for corruption. If other gamblers know that a player who regularly bets on himself to win is suddenly not betting against a specific team (or if an athlete who usually wagers $1,000 a game has changed one particular bet to $10), he’s sending other gamblers a signal: It’s an admission by an active participant that he is not confident. The game cannot be objectively viewed as a toss-up, which is necessary to any sport’s integrity. The outcome isn’t fixed, but it is compromised.

I’m not sure Klosterman’s guidelines apply here, simply because of the fact that Mayweather has never seemed un-confident about anything. This is normal behavior for him, even if there’s no record of him having ever bet on himself in the past.

Others have done so, however. According to a 2011 Montreal Gazette story, middleweight champion Bernard Hopkins won $100,000 after wagering he would beat Felix Trinidad in 2001 and then won $250,000 by beating Antonio Tarver in 2006. The practice is not without controversy, however. In 2010, British heavyweight David Haye claimed to have bet on himself to beat Audley Harrison in exactly the third round of their WBA title bout in Manchester, England. And that’s exactly what happened after the two boxers appeared to sleepwalk through the first two rounds (Harrison threw just 32 punches and landed only one of them, sparking a British boxing investigation into whether he should receive his purse from the fight).

Haye later clarified his comments to say he merely had recommended to friends and family that they bet on him to win in the third.

“I didn’t physically go into a betting shop and say here’s X amount of money,” he said, per the BBC. “What I did say is I would knock Audley Harrison out in three rounds. My prediction was the third round and I told a lot of people that and it was true.

“It makes the fight a lot more exciting for people. It did feel like I’d bet on myself because so many people had put money on it. If it had gone into the fourth round I would have felt guilty.”

British boxing rules forbid boxers from betting on themselves.

And then there’s the very strange case of Irish boxer Steven Donnelly, who was found to have bet on himself to lose his bout against Tuvshinbat Byamba of Mongolia at last year’s Olympics. Donnelly then went out and won the fight.

In any case, Mayweather will have to make a rather large wager to take home any sort of big gambling payday. Though his odds have fallen sharply as bets come in on McGregor, a heavy underdog, the Mayweather money line sits at anywhere from -450 to -700, depending on where you’re looking.

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