dark horse

A dark horse is a previously lesser-known person, team or thing that emerges to prominence in a situation, especially in a competition involving multiple rivals, that in theory is unlikely to succeed but has a fighting chance, unlike the underdog who is expected to lose. The term comes from horse racing and horse betting jargon for any new but promising horse. It has since found usage mostly in other sports, sports betting and sports journalism and to lesser extent in nascent business environments, such as experimental technology and startup companies. Origin The term began as horse racing parlance for a race horse that is unknown to gamblers and thus difficult to establish betting odds for. The first known mention of the concept is in Benjamin Disraeli's novel The Young Duke (1831). Disraeli's protagonist, the Duke of St. James, attends a horse race with a surprise finish: "A dark horse which had never been thought of, and which the careless St. James had never even observed in the list, rushed past the grandstand in sweeping triumph."