His opponent was reigning champion Tom King, whom he was widely expected to beat. Articles for the fight with each side staking £1000 were signed on 17 March 1863. After a strong start with several successful throws, Heenan faded, and King, landing a series of blows to Heenan's face, knocked him out in the 24th round. The result was controversial: many American observers later agreed that King had been given longer than the rules allowed to recover from a knock-down in the eighteenth round, and Heenan claimed some time after the fight that his subsequent collapse occurred because he had been drugged.