There’s been a ton of debate and discussion as to what it will mean for combat sports, if… if Conor McGregor defeats Floyd Mayweather on Saturday night. Well, according to the last man who battled Mayweather in 2015, if McGregor scores the upset on August 26th, it will be a serious blow to boxing.

If you follow boxing, then you know that man is Andre Berto, who faced Mayweather in what was, at the time, the latter’s retirement fight (although most observers believed “Money” would return to the ring at some point, in an effort to break Rocky Marciano’s record of 49-0). Mayweather won the bout via unanimous decision.

Recently Berto was a guest on “The MMA Hour”, and when the 33 year-old was asked what it will mean if McGregor defeats Mayweather, the welterweight said this (quote via MMA Fighting):

“If this were to be an upset, it would definitely be a big blow to the boxing game, for sure,” Berto said. “Definitely, definitely. It’s gonna be a big blow to Floyd’s legacy, as well. Just being undefeated and able to let some guy upset you and he’s an MMA fighter and he probably talks a little more shit than you talk. It’s gonna be tough for him to swallow if that happens.”

“It’s gonna be a real tough pill to swallow for the boxing game,” Berto added. “Especially for one of our top, top guys — probably one of the best in the game. That would be a tremendous pill to swallow. Of course, like I said, we’ve been going back and forth with the whole MMA thing for a long time. Boxing and MMA.”

Yup. There’s no question that if McGregor wins, it’s going to shake combat sports, and boxing in particular, to its foundation. After all, McGregor has never competed in a pro-boxing bout, which is something a lot of folks, particularly those in boxing, have repeatedly noted.

Really, even if McGregor lands some heavy shots on Saturday, and goes 12 rounds with Mayweather, it will be widely viewed as a win for the UFC lightweight champ.