I handily defeated the guy that was 10lbs (it was probably more like 20, we didn't have official weigh-ins) but this was a different time. I have to admit that I was afraid of him because he was ripped as hell but we only had to exchange a few blows for me to realize that his size was his only real advantage. He was trying to fight me standing up as well but as anyone who does any BJJ knows, your size isn't really an advantage on the ground either against someone who knows what they are doing - it can actually work to your detriment.
The deal was sealed kind of by accident. After taking a few jabs and shots to the body from kicks by me he tried to do some sort of "peekaboo" tactic that Mike Tyson used so effectively. However, this guy's defense sucked and he "peekabood" right into my knee on one approach. I of course was involved in the KO because it was my knee, but the fact that his head was coming forward in a very predictable manner every time we engaged meant it was immediate lights out for him when I connected.
This victory landed me a multi-fight contract (don't get excited, it was for very little money) and I think I let the confidence go to my head because I lost by decision in my 2nd amateur fight and I lost so badly in my 3rd that I don't even remember anything after the first round. The next memory I have after that fight is being in the hospital. It was my last fight.
But anyway, I do think that the confidence that comes along with knowing that you can handle yourself in a scrap is a very important one to have, especially as a man. I have a mantra now even though it is a more than 20 years since my amateur fights... "I'll never start fights, but i'll damn sure finish them."