Undefeated boxer Floyd Mayweather and mixed martial arts champion Conor McGregor traded barbs during a lively press conference in Los Angeles on Tuesday, delighting a rowdy crowd ahead of their August 26 fight in Las Vegas.

The media conference was the first in a four-day international tour promoting the bout.

The contrasts between the two were immediately apparent as McGregor danced around the stage smiling while Mayweather looked on stone-faced.

As is expected in the bout, McGregor was the aggressor, wasting no time bringing up reports that Mayweather earlier this month asked the IRS for more time to pay his 2015 tax bill.

“He’s in a track suit,” McGregor told the crowd of more than 11,000 people, who largely cheered the Irishman and booed the American. “He can’t even afford a suit anymore.”he said

Later when Mayweather, whose nickname is “Money” and who frequently uses cash as a prop, pulled out a $100 million cheque on stage, McGregor told him to “give it to the taxman”.

When asked about the tax issue, Mayweather said his attorneys were working on it and did not worry him.

“I just showed you all a $100 million cheque that I haven’t even cashed yet, so we ain’t tripping on that,” he told reporters.

The check appeared to be the $100 million he earned for his victory over Manny Pacquiao two years ago.

Mayweather was more subdued than the fiery 28-year-old, reminding reporters that even though he is a heavy favorite, he is 40 years old and that anything can happen in a fight.

He said he expected McGregor, who has never fought a professional boxing match, to try to pummel the defensive-minded Mayweather, who is putting his perfect 49-0 record on the line.