The boxer tried to place a big bet on himself.
Floyd Mayweather reportedly attempted to place a $400K bet on himself hours before his fight against Conor McGregor.
ESPN reports that Mayweather entered a Las Vegas sportsbook and tried to place the bet, but was unsuccessful and left "pissed."
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.
Mayweather would have won either of those bets, as he TKO'd McGregor 1 minute and 5 seconds into the 10th round.
ESPN says neither the Nevada State Athletic Commission nor the Nevada Gaming Control have rules on a fighter's ability to bet on himself.
Maybe Mayweather will be able to place a big bet on the rematch...