Ah, March Madness. It's what turns casual basketball fans into diehards, even if it is only for a month.
It's all about the buzzer beaters that dash title hopes and superhuman performances that etch previously unknown names into the history books of college basketball. It's about long-time coaches leaving the game with career-defining wins and Final Four runs straight out of dreamland.
The NCAA Men's Division I Basketball Tournament is the most exciting American sporting event. Period. It is because of the upsets. It's because of the underdogs that empower fan bases and ignite brackets.
Here are the 20 biggest upsets in tournament history.