MMA's biggest upsets Photograph By AP Photo/Branimir Kvartuc

Everyone loves an underdog. There is something uniquely pleasing, perhaps even life-affirming, about seeing a scrappy long shot pull himself up out of obscurity to defy the critics and beat the odds. There is a unique kind of joy in occasionally seeing the small fry topple the big fish. Whether it be by last-second Hail Mary, ninth-inning homer or first-round knockout, perhaps we all imagine we see a little bit of ourselves in these athletes who can for one night only make the impossible possible. At times it feels like mixed martial arts was tailor-made for the upset. In a sport this nuanced, this cerebral and this unpredictable, fans have learned from experience that the little guy always has a chance. In light of that -- and with Vitor Belfort poised to take his own shot at immortality at UFC 152 -- here's a look back at the five biggest upsets in MMA history --Chad Dundas