With the lucrative pay-per-view extravaganza to be decided only by knock-out, technical knock-out or disqualification, the two men went the distance in a bout most onlookers agreed would have been awarded to Mayweather had points been in operation.

To his credit, the 29-year-old Paul, who has 29 million YouTube followers, was able to put some pressure on Mayweather, the 44-year-old former five-division champion, who came in four weight classes lighter than his opponent.

The bout began quietly and descended into something of a wrestling match in round three, before Mayweather stepped his assault up a gear.

He had Paul retreating and looking tired after landing a series of punches in round four, then looked close to finishing proceedings towards the end of the fifth with a succession of body blows.

Paul coped with the barrage, however, and stood his ground through the final three rounds to earn considerable online support and praise from his rival.

"I had a great time moving with these young guys, test my skills and just to have some fun. He's a great young fighter, tough, he's better than what I thought he was," Mayweather said.

"He's a rough competitor. I was surprised by tonight. Good work. Good guy."

Paul said of Mayweather that it was "an honour to grace the ring with him".

"I don't want anyone to tell me anything is impossible ever again. The fact that I'm in here with one of the greatest boxers of all time proves that the odds can be beat," he said.

"You never know with this guy. I might go home thinking 'Did Floyd let me survive?' He's one of the GOATS and in many ways he controls this sport, that's what makes him great."

Australian Associated Press