This clip is from June 19, 1960. World heavyweight champion Ingemar Johansson appears as a mystery challenger on What's My Line the night before he defended his world heavyweight championship at the Polo Grounds against Floyd Patterson. Johansson had defeated Patterson in an upset in 1959. The rematch was Johansson's only title defense. Patterson won by a fifth-round knockout to regain the crown. (Perhaps Ingo should have been resting instead of appearing on live TV.)