The use of upset as a noun in sports writing to indicate an unexpected result in a contest dates to the late 19th century. It was a fairly common term dating back to 1877. From the New York Times of 17 July of that year:
The programme for to-day at Monmouth Park indicates a victory for the favorite in each of the four events, but racing is so uncertain that there may be a startling upset.
It is commonly claimed, however, that this use of upset as a noun stems from a classic 1919 horse race that pitted Man o’ War, probably the greatest race horse of all time, against an unlikely opponent named Upset.
During his career, Man o’ War lost only one race, the 13 August 1919 Stanford Memorial at Saratoga. Man o’ War was heavily favored to win, but lost to a horse named Upset. This, the legend goes, is where the sports term upset comes from. Man o’ War would face Upset in five other races, winning every one, but this, according the tale, one loss early in his career would be the one to make lexicographic history.
Most lexicographers and etymologists thought the story too good to be true, but no one could disprove it. Sporting usages of upset prior to 1919 just could not be found. Then in late 2002, researcher George Thompson, using the newly available tools of full-text online searching of the New York Times databases, turned up a string of sporting usages of upset dating back to the 1877 citation given above. There are numerous uses of the term in 19th century sportswriting, proving beyond a doubt that the term was well-established by the time Man o’ War lost his only race. Upset did not father a term, he was just well named.
(Sources: ADS-L; ProQuest Historical New York Times)
Copyright 1997-2013, by David Wilton