Considering that Brock Lesnar was being called the "baddest man on the planet" and was and probably still is one of the biggest draws in the UFC, his loss to Cain Velasquez has to be considered a major upset.
Well take into consideration what makes for a huge upset. First of all, the odds must be against you winning (most likely Vegas odds as well as the average fan of your sport).
And lastly, in my humble opinion there has to be people who care. Lots of people. My high school team won a few track meets that we weren't supposed to win, but I doubt people would want them on this list.
All that being said, here are my 50 greatest upsets of all time.