Floyd Mayweather has made the bold claim that he is the best boxer of all time.

Ali is generally considered the greatest fighter to ever step between the ropes, but Mayweather, preparing for his much-anticipated showdown with Manny Pacquiao on May 2, asked ESPN's Stephen A Smith: "How? He only fought in one weight class."

He added: "No one can ever brainwash me to make me believe that Sugar Ray Robinson and Muhammad Ali was better than me.

"But one thing I will do: I'm going to take my hat off to those guys and respect those guys because those are the guys that paved the way for me."

On Ali, he added: "Leon Spinks beat him when he had seven fights. They'd never put a fighter in there with Floyd Mayweather with seven fights. So are you going tell me that it's cool to lay on the ropes and take punishment and let a man tire himself out from beating you and then he basically fatigued?

"You hit him with a few punches and he go down and quit, and you want to be glorified for that?"