giant-killer
A person or team that defeats a much stronger opponent, especially in sports. Often used in the context of tournaments or upsets. The Japanese term 大物食い (oomonogui) is a near synonym.
See also: 大物食い
That team is known as a giant-killer.
In this tournament, another giant-killer has emerged.
Variant spelling with a middle dot, reflecting the English word boundary.
Borrowed from English 'giant-killer'.