By Joseph Santoliquito

PHILADELPHIA (CBS) — Floyd “Money” Mayweather knows something, and a hint of that came through during the final press conference on Wednesday prior to his fight with mixed martial arts star Conor McGregor.

The fight takes place on Saturday at the T-Mobile Arena on Showtime Pay-Per-View and is scheduled for 12 rounds in eight-ounce gloves.

Don’t expect it to go 12. Don’t even expect it to go seven.

Mayweather, who turned 40 on Feb. 24 and hasn’t fought since Sept. 12, 2015, said he is taking the fight “extremely serious,” though he broke training camp to do the late-night talk show circuit 10 days prior to the fight, something he never did in the past. Mayweather (49–0, 26 KOs) is an all-time great. He is a future hall of famer and he will break the unofficial record of Rocky Marciano’s 49-0 streak.

That will happen because of this: “I can fight, I can give it and I can take it, but for me to be 49-0, it’s obvious, I’m not receiving it, I’m giving it,” Mayweather said. “It’s going to be blood, sweat and tears, and that’s what we want to give people all around the world.”

Don’t expect that to happen, either. Mayweather is masterful at the art of hitting and not being hit. Though it’s been almost two years since he last fought, and though he’s 40, he’s still able to be in two places at once, and his opponents often swing at the wrong Mayweather. Some fans may forget that Mayweather was rocked and in trouble in the second round of his May 1, 2010 fight against Shane Mosley.

Then Money proceeded to win every second of every round after that. He does have a chin, and he also hits far harder than he’s given credit for. But it won’t be speed and tactics alone that dismantle McGregor; it will be endurance. Mayweather has been boxing since he was three years old. He’s used to going 36 minutes.

McGregor, on the other hand, averaged 8 minutes, 38 seconds in his last 10 UFC fights. That’s barely three rounds. “The Notorious” can spar 30 rounds a day, it won’t actually mean anything going against a seasoned pro who’s done it his whole life.

So when Mayweather says “In the Octagon, he’s undefeated standing up, he can do a lot of this … and I’ve been here plenty of times. After 21 years, I’ve been hit with everything and I’m still right here. One thing that you must know about the sport of boxing and combat sports, if you give it, you must be able to take it.

“With that being said, out of 47 opponents that I faced, I have brittle hands and I’m supposed to be a scared opponent. The last time I checked nobody is walking me down. It’s called smarts and having patience. Remember this, the same way you give it, you have to be able to take it.”

Apparently, word is out that McGregor (21-3, 18 KOs in MMA) can’t take it.

“When things don’t go his way, you see a little fold in Conor,” said Paulie Malignaggi, who sparred with McGregor and will be calling the fight with the Showtime team of blow-by-blow man Mauro Ranallo and color analyst Al Bernstein. “He’s a typical bully. Boxing fans don’t like bullies. They like people who fight back. I was nowhere in shape, and I wonder how brave he would have been if I was in any kind of shape. He’s only going to win with his explosiveness and intensity.

“He doesn’t hit as hard as everyone thinks he does. He thinks he hits harder than he does, and he’s better than he is. It’s like when you’re a little kid and you think you’re Batman or Superman. He’s not. Conor is not afraid of anybody, but once he starts getting beat up, there will be a change there. Fighters know when another fighter is looking for a way out.”

What will happen is McGregor approaching Mayweather cautiously, looking more so last than to win? Fighters, at any level, get easily gassed when overextending and missing punches. Without the proper endurance base of a world-class boxer, McGregor will be defenseless by the fourth round, open to anything Mayweather throws.

By the sixth round, one of two things could happen: Mayweather stops McGregor, who goes out gallantly on his shield, battered and swollen; or the more likely scenario, McGregor’s ego gets the better of him and rather than continue taking punishment and embarrassed, he finagles his way out by getting disqualified for a boxing move, like constant holding or pushing Mayweather’s head down after myriad warnings by the ref. Many watching will wonder what happened, despite being forewarned, while others who have a good idea will simply say: “I told you so.”