Upset (foaled 1917 in New Jersey) is notable as the only horse to have ever defeated Man o' War. Man o' War, who won 20 of his 21 starts, faced Upset in the seventh running of the Sanford Memorial Stakes at Saratoga Race Course on August 13, 1919. Losing by a neck, Man o' War had been fractious at the starting line and got a bad start, leaving close to last. He also carried 15 pounds more than Upset. The loss snapped a six-race winning streak by Man o' War.
|Breeder||Brookdale Stud Farm (Harry P. Whitney)|
|Owner||Harry Payne Whitney|
|Trainer||James G. Rowe Sr.|
|Sanford Memorial Stakes (1919)|
While it is widely believed that the term "upset", referring to a surprising loss, originated with this horse, that is not the case. The use of the word in horse racing dates to at least 1877, and the meaning "to overturn" or "overthrow" appears to be even older.
- "Kentucky Juvenile Wins First Running Of Sanford Memorial Stakes". Daily Racing Form at University of Kentucky Archives. 1913-08-24. Retrieved 2019-01-08.
- Van Ness, Fred (August 13, 1919). "A Horse Named Upset Beats Man o' War". The New York Times. Retrieved 30 August 2015.
- Schwartz, Larry. "Man o' War came close to perfection". ESPN. Retrieved 30 August 2015.
- "Sports Legend Revealed…". Los Angeles Times. 2011-05-10. Retrieved 2019-01-09.