It's fairly easy if you have 10 sensitivity and you have someone running straight for you. Of course, I almost have an unfair advantage of 3G internet and it's lag, but it works both ways. I've show-stopped people assassinating me by punching them before they do it, and I've had the same happen to me too.
EDIT; Derp, forgot. Just jump over them, turn around in mid-air, and punch before you land.
[Edited on 11.06.2011 1:28 PM PST]