The UFC history books are littered with stunning victories that few saw coming.
While many sports have their underdog stories, MMA gives those overlooked an opportunity to shock the world with a single punch. The unpredictability of UFC fights is part of what has helped the promotion explode in popularity over the past several years.
It's not as though low-profile fights are the only ones ending in major upsets, either. Several UFC championships have traded hands because of mind-boggling results.
Based on fight importance, grandeur of victory and matchup betting odds, these are the 25 greatest upsets in UFC history.