At class I referenced the use of the Guard game in the early UFCs by Royce Gracie
Royce was the smallest person in the events and he won 3 of them, against bigger, stronger men, by fighting on his back and submitting them with the choke or armbar
I posted Rener and Ryron's breakdown of the Ken Shamrock match at the blog last year:
whitetigermartialarts.blogspot.co.uk/2012/07/ufc-1-gracie-shamrock-breakdown.html
In this match Royce does the shoot, and is sprawled, stands and pulls guard, goes for the mount and ends up with an unconvential rollover and a sleeper, all in about a minute