In combat sports being heavier is, in and of itself, considered a significant advantage.
Therefore, a smaller fighter can usually only win against a heavier opponent if the fight is otherwise biased towards the lighter competitor. Examples:
- If the heavier opponent is monstrually obese to the point that their weight gimps them (eg Yarbrough vs Hackney?);
- If the lighter fighter has significantly more skill to the point that if there was no weight disparity the fight would be clearly unfair;
- If the fight is a scripted, theatrical performance rather than genuine competition.
It is rare to see a fair openweight competition nowadays, however, they were more common in the past. Was there any event when a significantly smaller fighter could actually overpower the heavier one in a fair fight? This means that the heavier opponent did not have ridiculously large body fat percentage, the fight was not otherwise biased towards the lighter fighter to the point that if there was no weight difference it would be unfair, the fight was not scripted and there were no other loopholes I failed to predict here?
NB: I tagged this question mma, boxing and amateur wrestling because I'm interested in any combat sport here and that which sport has the highest chance of this happening can perhaps be considered a part of my question?