Floyd Mayweather was on the attack, branding Conor McGregor a quitter as the four-stop tour hyping their cross-combat superfight hit New York.

“Eejit” and “Circus Clown” were the tamest epithets the former welterweight king, who retired from boxing with a perfect 49-0 record in 2015, threw at McGregor, one of the biggest stars of mixed martial arts.

“(He) didn't quit once, didn't quit twice, quit three times!” said Mayweather. “”Real fighters never give up.”

McGregor, a two-division champion in the Ultimate Fighting Championship, has conceded three defeats in 24 bouts, all by submission.

The two men are set to face each other in a boxing ring in Las Vegas on August 26 in what could be the richest fight in history.

Thursday's show at the Barclays Center, home of the NBA's Brooklyn Nets, drew a pro-McGregor crowd of more than 13,000.

It was the third such production in three days, with one more scheduled for London on Friday aimed at pumping up interest in the bout — although both men seemed to be running short of inventive invective even if the animosity between them is actually growing.

McGregor eschewed his sharp-tailored suits for a bare chest and white fur overcoat — which he swept from his shoulders as he took the stage to offer a flexed-arm pose that inflamed the crowd.

The Irishman then paced impatiently as Mayweather, draped in an Irish flag, made his way to the stage and they took their positions for the ritual staredown from opposite sides of the podium.

A giant step forward from each had them nose to nose and brought more cheers from the crowd before McGregor launched into a lewd, crude address.

“No one's going to stop me walking around this place like I own it,” he said.

Mayweather, meanwhile, was all indifference until it was his turn to launch into his profanity-laced response.

After a little back-and-forth with the crowd, he showered McGregor with handfuls of dollar bills from his backpack — a day after McGregor mocked the paltry stash of cash “Money” had brought to their promotional stop in Toronto on Wednesday.

“They're all ones!” McGregor said.

“Because that's all you're worth,” Mayweather replied.

Mayweather, one of the most accomplished defensive fighters in history, admits there's a level of uncertainty in the entire undertaking.

Something different

”Nobody knows that squared circle like me,” Mayweather told reporters. “I know angles. I know where to touch you at. I know what you don't like. I don't have to watch your tapes. That's something I'm blessed with.

“But, he's unorthodox,” Mayweather added. “So it'll definitely be something different in the ring. I just have to keep my composure.”

But McGregor says he's relishing his underdog role — and will adapt just fine to the boxing ring.

“I have a very high fight IQ,” he said. “I understand when to go and when not to. I'm very confident whether it's in a ring or an octagon … I'm going to have my way with him.”

In the meantime, McGregor said, the whirlwind promotional tour wasn't wearing thin for him.

“I'm not tired of this,” said. “It's really a lot of fun. We'll keep it professional for now.

“Floyd is saying a lot about me tapping out, but he's never had a true fight,” McGregor added. “He knows nothing about the game that I'm involved with. We'll see who is quitting on August 26.”