Translation guide
A person or thing that is little known but unexpectedly successful or likely to succeed.
Describing a person or team in a competition who is not well-known but may win or do very well.
ダークホース is a direct loanword and used in general contexts. 穴馬 is originally from horse racing and carries a nuance of an underdog with long odds. 穴馬 can sound slightly more colloquial or sports-specific.
He is attracting attention as a dark horse.
Direct loanword from English, widely understood in sports, business, and entertainment contexts.
He is the dark horse in this election.
Literally 'hole horse', originally from horse racing, meaning an unexpected winner. Used metaphorically for people or teams.
That team is a dark horse.
Literally 'eye of the typhoon', used for a person or team that causes an upset or becomes the center of attention unexpectedly.
She became the dark horse of the tournament.
That candidate is a dark horse.