Conor McGregor has been boasting that Floyd Mayweather would be lucky to make it out of the second round against him, but Mayweather has some promises of his own for the UFC star turned boxer. Mayweather guaranteed a knockout in the fight, something that he hasn't done since 2011 against Victor Ortiz. That knockout was considered controversial because the ref was not yet looking when Mayweather dropped Ortiz, and his last true KO was against Ricky Hatton in 2007.

But on Wednesday, Mayweather was poised as ever talking to reporters about the fight.

"The same way he talking about -- he's giving it -- hopefully he can take it... but once again -- remember what I said -- 100 percent chance this fight won't go the distance," Mayweather said.

With his best asset being his mobility, Mayweather doesn't necessarily need to knock anyone out boxing. However, he stressed that one way or another, there is no way that the fight will go 12 rounds if either fighter has their way.

"I say I guarantee it won't go the distance," Mayweather said via ESPN. "He says it's not going the distance. I say it's not going the distance. So it's obvious we going to come out from the opening bell and drop bombs."  

McGregor, of course, believes that he has the edge if the fight stays short.

"Floyd can talk about whatever he wants to talk about. He can talk any kind of trash he wants, because he's talking to the new God of boxing," McGregor said. "If people are overlooking my size, power and youth, they shouldn't be. I'm very confident in those attributes. I believe I'll knock him out early. If you look at the way I fight, I am a fast starter. I come out and bang people right away. With 8-ounce gloves, I don't see him lasting more than one or two rounds."

The 8-ounce stipulation was a late addition, as the fighters were initially slated to wear 10-ounce gloves. It can benefit both the quick-jabbing Mayweather or the heavy-hitting McGregor. But either way, neither fighter wants a repeat of Mayweather-Pacquiao in 2015. Both combatants want the match to end with the other's face on the mat. We will find out once and for all Saturday night on Showtime PPV, beginning at 9 p.m. ET.