Somehow, the more I think about it, the more I give Manny a good run against Mayweather. I agree that skill wise, Mayweather is the best. However, the recipe to beat Mayweather lies in lot of pressure, lot of speed volume in punching and good power. Castillo in their first fight should have won, he unsettled Mayweather by being very aggressive and throwing loads of shot. Hatton made quite well in the first few rounds with his bull pressure, only to get beaten by lack of skill. Pacquiao is a different beast though, he has speed the two others didn't have, a much better firepower and he can throw shots endlessly without tiring. And when he lands, it hurts. If he nailed down Cotto, Marquez or the very durable Morales, he can sure knock down Mayweather. I could imagine a fight where Mayweather wins the first few rounds based on skills but get hurt in the middle run by some of the shots that will eventually land to be knocked out toward the end of the fight. At least, PAcquiao has all the very rare and hard to combine ingredients to make it happen.