Takanori Gomi, the #1 Lightweight Fighter in the world.
Diaz could certainly get KO'd but he's faced bigger, more dangerous strikers and not gotten knocked out and he has the major advantage on the ground.
I think some PRIDE snobs are going to be surprised by the outcome of this one. Nick Diaz agrees:
I don't think he has anything to offer that I haven't seen before. I think I've fought tougher guys than him. The guys I've fought hit harder, were better wrestlers and better grapplers. What does he think he'll be able to do to me? I'm not intimidated at all and if he thinks he can knock me out that's fine. I think he'll be the one getting an ass beating so I hope he's ready.