Conor McGregor Floyd Mayweather
Conor McGregor, pictured during the Floyd Mayweather Jr. v Conor McGregor World Press Tour at SSE Arena on July 14, 2017 in London, England, isn't nearly as much of a betting underdog as he once was. Getty Images

In many respects, a win for Conor McGregor over Floyd Mayweather on Aug. 26 at T-Mobile Arena in Las Vegas would be the biggest upset in modern sports history. Crossing over from MMA, the UFC’s No.1 star would be hard pressed to defeat even an average boxer, let alone the greatest of his generation that has a record of 49-0.

Following the four-day tour to promote the fight, however, more and more people seem to be giving McGregor a shot. The betting odds continue to move, making McGregor an even smaller underdog.

READ: How Many PPV Buys Will Floyd Mayweather vs. Conor McGregor Do?

On Tuesday, announced that McGregor’s odds were just +350, putting Mayweather at -500. While the odds have since shifted back to -600/+400, it was the best chance McGregor had been given since odds were created for the fight late in 2016.

Six months ago, Jeff Sherman of the Westgate Las Vegas SuperBook said Mayweather would be a -2500 favorite with McGregor getting +1100 odds. The odds dropped to -1100/+700 when the fight was made official in the middle of June, and the betting public has continued to support McGregor ever since.

McGregor, of course, believes he will win, predicting that he’ll knockout Mayweather within four rounds. UFC president Dana White knows Mayweather has the advantage, but he wouldn’t be surprised to see his fighter shock the world.

“The reality is Floyd Mayweather will be 41 years old this year,” White said at a press conference at Barclays Center before Day 3 of the press tour. “Conor McGregor is a southpaw. If there’s any kink in that armor if you want to look at one thing, you could call it when Floyd goes up against southpaws. McGregor’s 28 years old, and he hits like a truck. When McGregor hits people, he hurts them, and when he hurts them, he finishes them.

“In a 12-round fight, is Conor ever gonna hit him once? I believe he will. I believe he’ll hit him more than once, and we’ll see what happens when Floyd gets hit.”

White admits that McGregor can’t beat Mayweather in a 12-round fight, saying that the UFC star is a fighter and not a boxer. He didn’t make much of the training video that McGregor released of himself on social media, which emphasized the gap between the boxing skills of Mayweather and the MMA star.

When Mayweather Promotions CEO Leonard Ellerbe was asked about the video, he claimed that McGregor attempted to look amateurish on purpose.

“Conor McGregor is a smart dude,” Ellerbe said. “He’s a smart dude. Do y’all actually believe that footage he put out there was real? I’m just being honest. Do you honestly think that he put that footage out there and it’s real looking the way it looked? C’mon now. That man, he has Dana and those guys, they know what they're doing. Because guess what? He tricked all y’all. Each and every one of you. He looked slow on the bag, he’s doing this and doing that. Y’all can fall for it. We’re not.”

Even Mayweather has said that McGregor has a chance to win. While the undefeated boxer has boasted about what he will do on Aug. 26 when standing face-to-face with McGregor, the 40-year-old hasn’t sounded nearly as confident when talking to the media. Mayweather continues to remind everyone of his age, saying he isn’t nearly the same fighter that he was when he was in his prime.

Mayweather’s camp is doing what it needs to do to promote the fight. If they want it to set a record for pay-per-view buys and truly make this the biggest fight of all time, a portion of the fan base has to believe that McGregor can win.

Major upsets are not unheard of in boxing. On July 1, Jeff Horn picked up a stunning and controversial victory over Manny Pacquiao. A few months earlier, Roman Gonzalez was considered by many to be the best pound-for-pound boxer in the world, and he suffered his first-ever defeat with a loss against Srisaket Sor Rungvisai.

READ: Did Conor McGregor Get Knocked Out Training For Floyd Mayweather Fight?

Still, there are plenty of fans that don’t think Mayweather can lose. McGregor admitted that the boxing world will “freak out” if he can become the first fighter to ever defeat Mayweather, arguably the best defensive fighter of all time.

“Any damn thing can happen in a fight, that’s why you fight the fight. And the more of you guys that say that guy don’t have a chance, I know he’s sitting over there licking his chops,” Ellerbe told reporters in Brooklyn. “He’s got just as good of a chance as anybody else does.”