An upset is a victory by an underdog team. In the context of the NCAA Division I Men's Basketball Tournament, a single-elimination tournament, this generally constitutes a lower seeded team defeating a higher-seeded (i.e., higher-ranked) team; a widely recognized upset is one performed by a team ranked substantially lower than its opponent. The NCAA defines a tournament "upset" as a victory by a team seeded 5 or more lines below its defeated opponent.