Since entering the UFC in 2013, Conor McGregor has been able to push the envelope whenever he’s tried to.

His list of accomplishments in the Octagon is long. Four years after joining the cage fighting organization, his biggest opportunity has been realized in the form of a matchup that seems impossible—facing legendary boxer Floyd Mayweather in the boxing ring.

On Saturday, Aug. 26, the two men will face off in what’s being lauded as a “money match” that could change the history of each man’s sport forever.

McGregor has been lauded in mixed martial arts circles for his ability to envision and attain heights that have evaded the grasp of the average UFC fighter. The Irishman has been the company’s biggest star, apart from Ronda Rousey, and for good reason. McGregor’s ability to promote himself made him a star before he even arrived at the Octagon in 2013. He was there for the company when Rousey was gone for almost all of 2016, headlining three of the organization’s biggest-ever shows. He’s headlined four of the UFC’s five most commercially successful shows, achieving at least 1 million buys for the last four pay-per-view matches he’s headlined.

UFC President Dana White admitted earlier in 2017 that he was aiming to make this fight for McGregor as a display of gratitude for what “The Notorious” has done for the company.

But in granting McGregor his biggest payday to date (he’s expected to make more than $100 million), White has taken a huge risk. McGregor stands to make more against Mayweather than he has in his entire UFC career. From a purely financial standpoint, McGregor would have no reason to return to the Octagon after the fight, and that has to be a major red flag for White and the rest of the UFC.

McGregor, a sizable underdog, has cleared so many hurdles just to get to the fight, so meeting Mayweather in a boxing ring doesn’t appear to be that troublesome anymore.

However, Mayweather still represents the biggest challenge in all of combat sports. His perfect 49-0 record has withstood tests from talented fighters like Miguel Cotto, Manny Pacquiao, Oscar De La Hoya and Canelo Alvarez, and none of them had to contend with switching to an entirely new sport.

McGregor’s punching power in the MMA won’t necessarily translate to the boxing ring. In the UFC, fighters wear four-ounce gloves, minimizing the padding covering a fighter’s fists. In Nevada, matches taking place at the 154-lb. weight limit are sanctioned to be fought with 10-ounce gloves, although the Nevada State Athletic Commission (NSAC) voted unanimously Wednesday, Aug. 16, to use eight-ounce gloves. It makes sense, when one considers the fact that a man is making his professional debut against one of the greatest pound-for-pound boxers of all time.

Even considering the size of the gloves, Mayweather has built a reputation and a perfect record as a defensive wizard. The 40-year-old has been able to neutralize every single man he’s faced as a professional. McGregor’s offense in MMA is based around a counter-striking attack, usually goading the other fighter into running into his left straight. While his punches’ success in the UFC is undoubted, their effectiveness in boxing will be questioned, especially against a specialist like Mayweather.

The promotion for the fight was based around a four-stop global press tour. In July, the fighters and their respective entourages visited Los Angeles, Toronto, Brooklyn and London in a four-day stretch. The tour started on an awkward note, as McGregor looked completely unprepared for the format in Los Angeles, but he was able to recover in Toronto. It was in Canada where the two fighters peaked in their ability to promote the fight. Showtime Sports, the main promoter for the fight, likely hoped the press tour would finish there.

However, in Brooklyn, each fighter missed expectations wildly. It’s foolish and shortsighted to expect a pair of men who will literally try to punch each other into unconsciousness to greet each other with class and dignity, but McGregor and Mayweather left everyone in attendance and the thousands streaming the event online disappointed. McGregor, whose “Dance for me, boy!” line prompted accusations of racism earlier in the tour, came out with a cringeworthy diatribe on how he couldn’t be racist because he was “half-black from the waist down.”

Mayweather, who could have walked away a winner on the tour stop had he just stayed silent, returned with a slew of misogynistic insults. In London, the Grand Rapids native made things worse by refering to McGregor with a homophobic slur. It was a black eye on what had looked like a major success until that point.

While the press tour was hit-or-miss, the fight has done a solid job of promoting itself otherwise. The pay-per-view record for a boxing match stands at 4.9 million buys for Mayweather versus Pacquiao in 2015. Dana White thinks that the record will be smashed Saturday, Aug. 26.

Whether or not buyers will get something worth the $100 they’ll be paying is another matter.