grudge match
A match or contest held to settle a long-standing grudge or bad blood between opponents. Often used in sports, martial arts, or dramatic contexts.
The grudge match between the two teams turned into an intense battle.
Since that grudge match, the two haven't exchanged a single word.
Similar in meaning but broader; can refer to any fateful showdown, not necessarily a formal match.
Compound of 遺恨 (いこん, 'grudge') and 試合 (しあい, 'match'). The exact historical derivation is uncertain, but the term is conventionally associated with settling old scores through competition.