Photo: Isaac Brekken/AP

Floyd Mayweather went into the M Casino sportsbook Saturday afternoon and tried to plunk down $400,000 in cash on at least one bet on himself, according to this ESPN report.

Mayweather attempted to place a $400,000 bet on the fight ending under 9.5 rounds at -200 odds, but according to a source, there were concerns over the legality of a fighter betting on anything other than a straight win, which caused a delay.

Mayweather then tried to bet on himself to win by knockout, but was unhappy about having to wait to place the wager and left without getting the bet down, the sources said.

“He was pissed,” one source said.

Had Mayweather successfully made the bets at the M sportsbook, he would have won them both; the fight indeed lasted fewer than 10 full rounds, and he did, in fact, win by a knockout. If you are the sort of person who assumes the fix was in, Mayweather attempting to bet a small fortune on what turned out to be the exact outcome could certainly support that belief. On the other hand, if you are the sort of person who believes Conor McGregor was a trumped-up stiff, and Mayweather’s style of fighting since, oh, mid-1998 all but guarantees that anyone in a boxing ring with him will last until at least the middle rounds, the fact that Mayweather was confident it would go off exactly the way it did is no surprise.

“I think that we bet 100 on 9½,” Mayweather told ESPN’s Sal Paolantonio after the fight. “I gave my guy six figures to go bet. I have to make sure he bet because earlier today I went to the sports book to bet and they wouldn’t let me bet.”

Mayweather later told SportsCenter he gave a friend $400,000 to bet, but that the friend was only allowed to place a bet for $87,000.

ESPN reported earlier Saturday that at least six different bets of at least $1 million were placed on Mayweather at various Las Vegas sportsbooks in the weeks leading up to the fight. The volume of betting still tilted wildly towards the long shot:

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.

God help you if you plunked down something significant on the guy from the wrong sport beating an undefeated champion.