Floyd Mayweather has refused to back off from comments declaring himself a better fighter than Muhammad Ali.

Mayweather said he respects Ali's great career and the things he did outside the ring.

He believes he's done as much in boxing as the legendary former heavyweight champion ever did, without the losses that Ali suffered in his career.

Current heavyweight champion, Wladimir Klitschko, told a group of reporters in New York on Tuesday that Mayweather shouldn't be so boastful.

"I think people call the king the king, [it's] not the king [who says] 'I'm the king.' So people make others somebody that he is or that he's not. So that's people's opinions," Klitschko said.

While Mayweather's place in history may be in debate, there's no debate he will make the biggest purse ever against Manny Pacquiao on May 2nd.