High Quality Content by WIKIPEDIA articles! An underdog is a person or group in a competition, frequently in electoral politics, sports and creative works, who is popularly expected to lose. The party, team or individual expected to win is called the favorite or top dog. In the rare case where an underdog wins, the outcome is an upset. These terms are commonly used in sports betting. The use of the term is believed to have come from the blood-sport known as bear-baiting where the "top-dog" was trained to attack the bear`s throat and head, and the "underdog" was trained to attack the bear`s underside. The top-dog had a better chance of surviving and of beating the bear, whereas the underdog was more likely to die.