When Sonny Liston declined to return to the ring after the seventh round, surrendering the heavyweight boxing championship in 1964, the media—which had mostly gambled against him—was forced to cope with Cassius Marcellus Clay's "tongue and magic," as TIME phrased it. He was undefeated, with 26 wins (22 by knockout) over four years. Clay returned on February 8, 1968, at Madison Square Garden in New York City. He took part in a tournament called "World Championship Boxing" organized by Jim Delligatti, which included opponents named Ali Mohammed and Alfredo Perez. The winner would become champion of the world. Clay defeated both opponents by KO in the first round. He then announced that he was quitting the sport. After leaving the ring, he changed his name to Muhammad Ali and began a career as a civil rights activist. He helped integrate sports in Alabama and became one of the first black athletes to receive a professional contract. In 1967, he joined the Nation of Islam and adopted the name "Cassius Clay." After leaving the group in 1971, he regained his title as champion boxer and was awarded $3 million (about $12.5 million in today's dollars). He continued to fight until he was knocked out by George Foreman in Zaire (now known as Congo)