Conor McGregor and Floyd Mayweather were both knocked out in the third round of their world tour on Thursday at the Barclays Center in Brooklyn.

Their performance Thursday in selling – attempting to sell, really, because they couldn’t have convinced a single person to buy the show with that effort – their Aug. 26 boxing match at T-Mobile Arena was profane, disgusting and appealed only to the lowest common denominator.

For all the fans, and potential pay-per-view buys they gained on the tour’s first two stops, on Tuesday in Los Angeles and on Wednesday in Toronto, they had to lose just as many after that classless performance on Thursday.

The tour wraps on Friday in London, but it probably should have wrapped after Wednesday’s event in Toronto.

It’s not like Mayweather and McGregor were models of decorum on the first two stops, but anyone who had even a modicum of interest in the event knew going in what it was all about: It was going to be taunts, trash talk and below-the-belt cheap shots.

McGregor made a few missteps the first two days, particularly when he twice called Mayweather “a boy” and told him to dance. It is denigrating to African-Americans and was in extremely poor form.

It was edgy, but it wasn’t the gong show that Thursday became. Any of the good moments on Tuesday and Wednesday were swallowed whole by their dive into the gutter in New York on Thursday.

McGregor entered first, and he was wearing a white mink coat with a dragon on the back, no shirt and floral pants. Mayweather followed, walking down a ramp wrapped in the Irish flag to taunt McGregor. When he reached the stage, Mayweather disrespectfully dropped the flag on the ground.

That was the high point of the show.

McGregor clearly ran out of material the first two days. His jokes mostly fell flat or crossed a line of decency, and he was way out of date.

When he first got the microphone, he bellowed, “What’s up New York City?” and seemed to have the crowd in the palm of his hand. But then he said, “50 Cent’s a bitch,” a cringe-worthy comment and one which made no sense given Mayweather and the rapper, whose real name is Curtis Jackson, haven’t been friends in years.

This tour is all about pushing the edge, two great fighters who are also natural promoters and showmen trying to rile up the fan base to convince them to drop $100 to buy the pay-per-view of the fight.

It worked well in Los Angeles and Toronto, even with several tasteless exchanges, and their performances seemed to change the attitude toward the fight.

When the tour began, there were quite a few, particularly boxing fans, who were questioning why a fight between one of the greatest boxers ever against an MMA fighter making his boxing debut was put together.

But in a span of a few hours on Tuesday and Wednesday, Mayweather and McGregor brought it to life with their wit, their passion and their natural salesmanship abilities.

Because of that, the tenor of the conversation seemed to shift from, “Why are they doing this fight” to “This fight is probably going to set the pay-per-view record.”

And then came Thursday’s debacle.

It’s clearly been a physical grind. McGregor flew to Los Angeles from his home in Ireland, then with just one day to rest, did the news conference Tuesday, flew to Toronto for Wednesday’s event and then went on to New York for Thursday’s show.

Undoubtedly there was fatigue, but it doesn’t excuse the loss of all sense of class or dignity.

McGregor had obviously heard some of the commentary about the tour’s first two stops, when he was criticized for referring to Mayweather as a boy.

McGregor said he wanted to address race and then made an extremely poor joke that wasn’t close to funny and which fell completely flat.

He said, “A lot of you in the media seem to be saying I’m against black people. That’s absolutely ridiculous. Do they not know I’m half black? I’m half black from the bellybutton down.”

If that wasn’t bad enough, he added, “Here’s a present for my beautiful black female fans.”

He then began to swivel and gyrate his hips like Elvis Presley once did.

It was raunchy and disgusting, but things didn’t get much better when Mayweather took over. Every other word out of his mouth was a curse, and at one point, he nearly created a riot when he shouted, “Form Voltron,” and his massive bodyguards surrounded McGregor.

Nothing happened, but Mayweather pulled out a handful of dollar bills and showered McGregor with them while referring to him as a stripper.

None of it was fun. It wasn’t entertaining and it sure couldn’t have helped to sell tickets or pay-per-view.

The tour concludes Friday in London and it’s about time.

Since the tour dates were announced last week, it was assumed that London would be the most over-the-top stop of the four. They lost their way, badly, in New York.

The best it seems one can hope for at this point is for the London stop to not be a disaster.

Friday had best be about damage control, because they did immeasurable damage to themselves, their sport and their event Thursday with the low-brow show they put on.