great white hope
Something or someone that is expected to succeed. For example, Mark is the great white hope of the international division. This expression dates from the early 1900s, when heavyweight boxing champion Jack Johnson, who was black, seemed invincible and the term was used for any white opponent who might defeat him. It gained currency as the title of a Broadway play and later (1970) a film. By then it had been transferred to anyone of whom much was expected.