"The Money Fight"

Floyd Mayweather Jr. vs. Conor McGregor, also known as "The Money Fight" and "The Biggest Fight in Combat Sports History", was a professional boxing match between undefeated eleven-time five-division boxing world champion Floyd Mayweather Jr. and two-division mixed martial arts (MMA) world champion and at-the-time current UFC Lightweight Champion Conor McGregor. The match took place at the T-Mobile Arena in Paradise, Nevada, on August 26, 2017 at the light-middleweight weight class (154 lbs; 69.9 kgs). It was scheduled for twelve rounds.

Mayweather extended his professional boxing undefeated streak to 50 victories and 0 defeats (50–0), surpassing the 49–0 record of Hall of Famer Rocky Marciano by defeating McGregor by technical knockout (TKO) in the 10th round. Mayweather announced in his post-fight interview that he had fought his final boxing match, and would retire from the sport. McGregor said in his post-fight interview that he would be willing to box again, and that he would return to mixed martial arts and the UFC. Mayweather's guaranteed disclosed paycheck was $100,000,000 and McGregor's guaranteed disclosed paycheck was $30,000,000.However, the purse for the two fighters is expected to be substantially higher for each, with Mayweather reportedly earning over $300,000,000 from the fight and McGregor earning $100,000,000.

During his successful UFC mixed martial arts career McGregor maintained an interest in boxing and entertained the idea of a "money fight" with Mayweather. Mayweather reportedly talked to Freddie Roach to train McGregor for the fight in case it would happen. UFC president Dana White dismissed the rumors of a fight with Mayweather on The Dan Patrick Show, stating that Mayweather would have to contact him since McGregor was under contract with the UFC. White even went as far as stating, "Here’s what I think the chances are [of the fight happening]: About the same of me being the backup quarterback for Brady on Sunday," referring to Super Bowl LI. In January 2017, it was reported that the two parties had entered an "exploratory phase" in negotiating a potential match between Mayweather and McGregor. On The Herd with Colin Cowherd, White openly offered to pay Mayweather $25 million to hold the proposed bout during a UFC event. He also predicted that pay-per-view viewership of the hypothetical bout could possibly rival Mayweather vs. Pacquiao.On March 7, 2017, Mayweather called upon McGregor to "sign the paper" and "make it happen", arguing that "if Conor McGregor really wants this fight to happen, stop blowing smoke up everybody's ass." On March 10, 2017, Mayweather stated that only a fight with McGregor would make him come out of retirement. On March 16, 2017, Dana White backpedaled on his stance against a Mayweather–McGregor bout and said that he would not deprive McGregor of a massive payday.On May 18, 2017, McGregor reportedly agreed to all of Mayweather's updated terms and signed the contract. The official confirmation of the fight was made on June 14. An international press tour was held from July 11–14.In July 2017, IBF super featherweight champion Gervonta Davis was reported to be going to participate in a co-main event. On July 19, additional undercard details were released. By that time, three names had been confirmed on the undercard, including British amateur boxer Savannah Marshall, who signed up earlier in the year with Mayweather Promotions, and Badou Jack, who stepped up to fight at light heavyweight. On July 26, 2017, it was announced that former welterweight titleholder Shawn Porter would be headlining the preliminary card, facing Thomas Dulorme. On August 17, Porter pulled out of the fight due to personal reasons, including a death in the family. He was replaced by Cuban boxer Yordenis Ugás. On July 29, it was reported that Gervonta Davis would defend his IBF junior lightweight title against former WBO champion Roman 'Rocky' Martinez. Martínez was dropped due to not having enough time to make the 130 pound [59 kg] limit. Instead Davis has been rescheduled to fight unbeaten prospect Francisco Fonseca. On August 9, 2017, it was announced that Nathan Cleverly would defend his WBA light heavyweight title against Money Team fighter Badou Jack.A mural was painted in McGregor's Dublin training facility, Straight Blast Gym, depicting McGregor hitting Mayweather with a left-handed punch.