Watch enough boxing and you'll witness many incredible rivalries. Though they have not yet fought, the most well-known feud today might be Manny Pacquiao-Floyd Mayweather.
Some rivalries are rooted in sportsmanship, and both fighters respect each other—like Arturo Gatti and Micky Ward, or Evander Holyfield and Riddick Bowe.
Then there are the ugly ones, the rivalries where there is genuine hate and animosity. The trilogy of fights between Marco Antonio Barrera and Erik Morales is a perfect example.
There's no manufactured hype around these matchups to sell pay-per-views or generate headlines.
Some people just don't like each other.
Go back through boxing history, and the sport is littered with these feuds. Some feature many of the same fighters, some are regional, some are outside the ring.
Which is the ugliest? It's not too difficult to figure out, and the rivalry remains mythical, even among fans who were too young to remember their last fight.
Let's jump into it. Here are boxing's 20 ugliest rivalries: