Who can knock-down the Pacman?

Over the years the more I watched of Ali’s boxing matches the more I was convinced that the secret to his success lay as much in giving a beating as it did in taking one. He could absorb punishment and there is nothing more defeating for a boxing opponent than to see that your punches don’t matter.
Manny Pacquiao is the same. I’ve watched the last four of his fights and nobody hit him as much as Miguel Coutto the other day. And Manny looked as fresh as roses.
Floyd Mayweather Jr do you have the balls? Manny does.