Though born Cassius Clay , he converted to Islam .
Though born Cassius Clay , he changed his name to Muhammad Ali in 1964 , shortly after defeating Sonny Liston in February of that year , for the world heavyweight boxing crown .
Though born Cassius Clay , he converted to Islam and changed his name to Muhammad Ali in 1964 , shortly after defeating Sonny Liston in February of that year , for the world heavyweight boxing crown .