Earp was a last-minute choice as referee for a boxing match on December 2, 1896, which the promoters billed as the heavyweight championship of the world, when Bob Fitzsimmons was set to fight Tom Sharkey at the Mechanics' Pavilion in San Francisco. Earp had refereed 30 or so matches in earlier days, though not under the Marquess of Queensberry Rules but under the older and more liberal London Prize Ring Rules. The fight may have been the most anticipated fight on American soil that year. Fitzsimmons was favored to win, and the public and even civic officials placed bets on the outcome.