Who is Sergio Oliva from Arnold: The Education of a Bodybuilder and what is their importance?

Sergio Oliva, a black Cuban, is known world wide as "The Myth." In 1969, Arnold wins the IFBB Mr. Universe contest in New York, but later discovers that his nemesis "The Myth" is not in the contest. He then rushes to enter the simultaneous Mr. Olympia contest, but he finds his confidence completely destroyed when he encounters Sergio. Arnold settles for second place, and for the next year, defeating Sergio Oliva is Arnold's prime motivation during his workouts. His efforts are rewarded in the Mr. World Contest in Columbus, Ohio when he finally beats "The Myth." Oliva doesn't take defeat graciously, which motivates Arnold to repeat his victory in New York in the following two weeks.