Four cities and three countries over four days. Floyd Mayweather and Conor McGregor traded verbal jabs from one city to the next. (1:37)

NEW YORK -- First came a half-hour of trash talk, cursing and ridiculous showmanship on Thursday night before 13,165 cheering fans at Barclays Center in Brooklyn as Floyd Mayweather and Conor McGregor roared through a profanity-filled, over-the-top commercial for their Aug. 26 junior middleweight megafight at the T-Mobile Arena in Las Vegas.

Floyd Mayweather vs. Conor McGregor Where: T-Mobile Arena, Las Vegas

When: Saturday, Aug. 26

TV: Showtime PPV, 9 p.m. ET

It was the third stop on their four-city, three-country world tour that began Tuesday in Los Angeles, hit Toronto on Wednesday and concluded Friday in London with some 50,000 fans turning out to take in the X-rated show in advance of the Showtime PPV fight many believe will break the all-time pay-per-view record of 4.6 million buys and some $600 million in revenue that Mayweather and Manny Pacquiao set in their long-awaited showdown in 2015.

But when Thursday night's performance was over, Mayweather toned things down when he came to the interview room to talk to the writers. One of the topics he touched on was his intent to return to retirement after the fight with McGregor.

He promised this is one and done.

"I gave [adviser] Al Haymon my word. I shook his hand, gave him a hug. I promised him, I gave him my word," Mayweather said about returning to retirement after the fight. "He said, 'Son, you don't want for nothing.' I own so much property, made so many smart investments. It's truly a blessing. I'm just thankful for being in this position; to be able to be at this age [40] and still be competing against guys in their 20s. It's a blessing, but if you look at it on paper, everything leans toward him [McGregor] on paper.

"He's bigger, he has a 74-inch reach, I have a 72-inch reach. I'm inactive. He's active. Youth is on his side. He's in his 20s, I'm in my 40s."

McGregor turned 29 on Friday, and while he does have those advantages over Mayweather (49-0, 26 KOs), one of the boxing's all-time greats, he has never boxed even though he is one of the best fighters in MMA and UFC's biggest star.

"But he's a stand-up fighter," Mayweather said. "We've never seen him lose standing up, so he can fight standing up. That's one thing he can do. He feels like he's the best. When I was competing I was the best. So I had to come back for this last hurrah."

Mayweather retired after he routed Andre Berto to retain his unified welterweight world titles in September 2015, vowing not to come back, even with the carrot of moving his record to a hallowed 50-0. But when McGregor began talking about a possible fight with him it was hard for Mayweather to ignore.

Before the fight was finally made last month, Mayweather responded to McGregor's comments by saying the only fight he would consider ending his two-year retirement for was one against the "Notorious" one.

Floyd Mayweather returned from retirement to face Conor McGregor on Aug. 26 in Las Vegas. Photo provided by Rosie Cohe/Showtime

"Did I want to come back? No, but once I threw bait out there and he said something I threw some more bait out there and he bit on it," Mayweather said. "I said, 'OK, now it's time for me to control the chessboard.' I'm no longer on the chessboard; I control the chessboard. Now we in this fight."

The reason he's in the fight is simple: He will make another nine-figure payday to add to the gargantuan $200 million-plus he earned for the fight with Pacquiao. That kind of money was hard to resist for the man who calls himself "Money."

Mayweather had no desire to return to the ring to fight a lesser-known opponent for a fraction of the money he will make as the huge favorite to easily beat McGregor.

"This move I made right here is not on the chessboard; it's controlling the chessboard. I can easily fight any fighter, anybody. I can fight one of you guys and make $35 million," he said, referring to the boxing writers he was addressing. "But why do that? My legacy is already set. This move I made right here it's unbelievable. They will talk about this business move at Harvard."

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