Floyd Mayweather Jr. dominated but failed to beat Logan Paul as the YouTube sensation went the full eight rounds with the boxing great in their exhibition showdown.

All eyes were on Hard Rock Stadium in Miami, where all-time great Mayweather and YouTube-star-turned-prizefighter Paul sensationally shared the ring on Sunday.

The exhibition bout featured eight three-minute rounds, with no judges and no official winner, though knockouts were legal.

In the bizarre cross-over-fight, there were concerns for Paul – who had lost his only other bout heading into a blockbuster showdown with Mayweather, who retired with a flawless 50-0 record in 2017.

Mayweather – typically patient – controlled the fight against a visibly tired Paul, who had a huge height and weight advantage and managed to unleash a flurry of punches though they barely troubled the 44-year-old.

"I'm not 21 anymore but it's good to run around with these younger guys," Mayweather said afterwards.

"He's a tough competitor, it was good action, had fun, I was surprised by him. Good work.

"... I had fun, I'm pretty sure he had fun and hopefully fans enjoyed it."

Paul, 26, added: "I don't want anyone to tell me anything is possible ever again.

"The fact that I'm in here with one of the best boxers of all times proves the odds can be beat.

"... Floyd Mayweather it was an honour, I hate being a d******** I love you guys."