Upset (competition)

An upset happens in a competition, mainly in electoral politics or sports, when the party popularly expected to win (the favorite), either loses to or draws/ties a game with an underdog whom the majority expects to lose. It is often used in reference to beating the betting odds in sports, or beating the opinion polls in electoral politics.
Examples include: Donald Trump beating Hillary Clinton in the 2016 presidential election or Alexandria Ocasio-Cortez beating Representative Joe Crowley in the 2018 midterms.