Williamson was deprived of an opportunity of lifetime. I was ringside at that fight. However, the more I've seen of him, it looks like he would have walked into something big and been put down for the count.
My first thought was Frank Bruno, who was unbelievably chinny, regardless of whether or not he got up to win (as some have suggested a factor in this thread). Frank had an almighty glass jaw, without a doubt. I'd also add Nigel Benn and David Haye to any list. Benn was KD a fair few times and won and lost a few of each, whilst David Haye is the definition of a 'chinny banger'. Controversially, I'll throw in Amir Khan, whose major weakness, I'm convinced, in the years to come will be his chin and also Kelly Pavlik, who only noticable weakness so far as I can tell is that he doesn't seem to have a granite chin. MTF
I thought it was round 3 against Zuniga, either way that was a hell of a fight as well, and no one seems to remember it, Zuniga should also be added to the list, he is a otugh bastard, but he can be dropped in a fight sometimes with ease, but he has gotten up to win by Ko.