After months of exchanging verbal jabs though media, Floyd Mayweather and Conor McGregor faced-off at a press conference in Los Angeles for their Aug. 26 12-round boxing showdown in Las Vegas. The 40-year-old Mayweather came out of retirement to stake his unbeaten 49-0 record against McGregor, the brash UFC lightweight champion.

Mayweather last fought in September 2015, beating Andre Berto via a close unanimous decision. "I'm the A-side. That's why this b---h had to come to the boxing ring,” Mayweather declared, referring to McGregor.

Mayweather even showed a nine-figure check, presumably from his bout against Manny Pacquiao, but McGregor told him that it was "for the tax man." McGregor also mentioned Mayweather’s $22.2 million tax problem with the IRS.

Around 20,000 people, mostly McGregor fans, attended the press conference at Staples Center. Aside from the Los Angeles press conference, Mayweather and McGregor will visit Toronto, New York and London to promote their fight.

The two fighters are guaranteed to earn in excess of $100 million each from the bout, in addition to shares from pay-per-view, which is expected to surpass the record set during Mayweather’s fight against Pacquiao. Darren Rovell of ESPN earlier reported that the Mayweather-McGregor showdown can equal or overtake the $623.5 million revenue of the Mayweather-Pacquiao clash. Rovell said earnings will come from ticket, pay-per-view, sponsorship, and merchandise sales.

McGregor determined to end Mayweather’s run

However, McGregor said he’s determined to end Mayweather’s unbeaten run, saying "he's f--ked" during the live broadcast. The press conference was also streamed live on YouTube and a number of other online platforms. The 28-year-old McGregor holds the distinction as the only mixed martial artist in history to hold two UFC championships at the same time.

While this will be a boxing match, McGregor is confident that he can beat Mayweather at his own game. "I don't fear him, I don't fear his limited set," McGregor said, adding that he will knock out Mayweather in four rounds.

McGregor underdog vs. Mayweather

McGregor is seen as an underdog in this fight due to Mayweather’s outstanding boxing record, but the UFC champion is determined to beat the former pound-for-pound king.

According to the latest odds from international bookmaker 5Dimes, Mayweather is a -1100 prohibitive favorite, while McGregor is a +700 underdog to win his first boxing match, be it amateur or professional.