After all, Hollywood is littered with movies that had huge expectations and media coverage ahead of their debuts, then flopped at box offices. Last summer's "Speed Racer," a US$120 million-plus production that generated only US$44 million in US and Canadian ticket sales, is just one example.

But executives at Summit Entertainment, the studio behind "Twilight," believe their vampire-meets-human romance has several factors in its favor. Most important, the film is based on best-selling books that are thought to be the next "Harry Potter" series, and it was made at a relatively low cost with two young actors who have won the hearts of "Twilight" fans.

"The movie has already been directed in the mind's eye of the reader," said Eric Feig, president of production for Summit. "That's always a challenge, to try to live up to those expectations," he said.

Fans of the books are extremely loyal. They camped out overnight this week to see the film's stars Robert Pattinson and Kristen Stewart at the movie's L.A. premiere, and last week, police shut down an event with Pattinson at a San Francisco mall when the unexpectedly large crowd got unruly.

Why the fervor? In her four-book series that has sold more than 17 million copies worldwide, author Stephenie Meyer created a new world of vampire lore for young readers.

Set in the US Pacific Northwest, "Twilight" follows the romance between a girl named Isabella "Bella" Swan who is a social outsider and an immortal vampire named Edward Cullen.

Their star-crossed love affair is complicated by the fact that other vampires are out to suck Swan's blood.