UFC superstar Conor McGregor has continued his trash talking with Floyd Mayweather Jr.

The two have been going back and forth over the last few months in the massive buildup to their highly anticipated bout at T-Mobile Arena on Saturday.

After Mayweather claimed the fight is "not going the distance", McGregor fired back by promising a brutal knockout win.

Even before McGregor spoke with reporters and fans, there was a clash between his massive entourage and Mayweather's, which was first to arrive at Toshiba Plaza.

McGregor is 21-3 as an MMA fighter, but has never been knocked down or out. All three of his losses have been by submission. Mayweather acknowledged that, but questioned whether McGregor had the stamina for a 12-round fight.

McGregor, 29, said he was up for the challenge and that youth will triumph over age.

The contest has more than it's fair share of critics.

One of them is Top Rank's CEO Bob Arum.

Arum believes the contest is a joke and should not be viewed as a legitimate fight.

The veteran promoter's recent comments have infuriated UFC President Dana White.

"This senile f***’s quote is ‘LeBron James is the greatest athlete on earth. Now if he fought Anthony Joshua…’ He’s comparing that fight to Conor – if LeBron James fought," White told reporters.

"Conor is a fighter. That’s the guy’s quote? I mean stuff like that bums me out. F***ing crazy. At the end of day people who say stuff like that don’t know anything about fighting. You know nothing about fighting. This isn’t going to be a boxing match. It’s gonna be a fight.

"Conor McGregor has knockout power in both hands, it’s eight ounce gloves and he’s going to go in there to knock out Floyd Mayweather. It depends on is Floyd really going to do what Floyd says he’s going to do?

"Is Floyd going to come forward? He might because he might believe he can hit Conor at will and he’s too fast. He’s a boxer, he might think that, but I tell ya if he gets clipped one time he will back off. Make no mistake this will be fight. Anyone here tell me the last time you saw a boring Conor McGregor fight? You can’t, it doesn’t exist."