stunning upset; totally unexpected result
Used for a major upset in sports, competitions, or any situation where the outcome is a huge surprise. Emphasizes the scale of the upset.
See also: 番狂わせ
The match was a stunning upset; the title favorite lost in the first round.
A totally unexpected result occurred in the election.
Compound of 大 (big) and 番狂わせ (upset, unexpected result). The exact historical derivation is uncertain, but the word is conventionally associated with major upsets.