Talk to Gary Ross, the writer-director of "Seabiscuit," and he'll tell you the book upon which his new film is based wouldn't have been atop the best-seller list in the United States if it was just about horse racing.

That's precisely why those behind the project have donned their blinkers and are coming out of the gates believing the Depression-era sports drama from Universal, DreamWorks and Spyglass Entertainment has a good chance of entering the winner's circle, bucking the odds of its Hollywood predecessors. The film opens today in wide release.

Across the board, horse-racing movies have produced very few boxoffice winners. Of the genre's 200 or so films, most have ended up in the also-ran category, with the notable exceptions of "National Velvet," "Phar Lap," "The Black Stallion" and "A Day at the Races."

The story, based on Laura Hillenbrand's "Seabiscuit: An American Legend," is about three men who come together and take an unlikely horse, Seabiscuit, to amazing victories that inspire a downhearted nation.

Ross says he had no trepidation about tapping into the definitive resource of his movie's subject.

"(Hillenbrand) knows the story better than I do," says Ross, a longtime horse-racing fan. "She is a custodian for it. I would literally not do anything without Laura's blessing. I'm not afraid of that."

A major challenge for the filmmaker was to adapt the real-life story for the screen. The tricky demands of creating composite characters, fictionalizing elements without losing the story's virtue, making sense of three converging stories and illustrating the superstar status of the horse required a close relationship between author and screenwriter.

"It is such a huge story," Ross explains. "It isn't so much how I compress it (but) how do I retain it? How do I keep the size, the spectacle, the scope, the breadth, this long saga alive and keep it compelling and entertaining?"

Ross and Hillenbrand shared a passion to convey to a new generation just how popular the horse was to the American people at a time when the sports landscape did not include the NBA, NFL, multimillion-dollar salaries and wall-to-wall television coverage.

"Seabiscuit was the greatest sports figure in America at a time when there were very few other sports figures," Ross says. "He was bigger than Joe DiMaggio (was in his day)."

In the 1938 match race between Seabiscuit and reigning Triple Crown winner War Admiral, an estimated 40 million Americans turned on their radio to listen to the underdog horse hold the lead from wire to wire and beat the champion racehorse by four lengths.

"On a per-capita basis, that would be the same as about 100 million Americans watching the Super Bowl," Ross says. "This was a sporting hero and a sporting event that's literally unparalleled in our lifetime, let alone then."

To give some perspective, the director adds, "(Seabiscuit) got more press coverage in 1938 than (President) Roosevelt and (Adolf) Hitler, that's how famous the horse was."

Although Hillenbrand had been warned that "authors always have such a bad time on movies," she was pleasantly surprised by her experience.

"Gary saw the story just the way I did," she says. "He saw the human element. He appreciated racing for its speed, color and drama. I knew no one could do the book word for word on the screen. (But what) I felt responsibility (for) through this whole process was to help ensure the movie depicted these people as they were because I feel indebted to these people I wrote about and responsible for their image."

The underlying themes of unlikely partnerships, overcoming hardships and the plight of the underdog are something the filmmakers are optimistic viewers will relate to.

"I hope the audience feels what (the characters') struggles (were), to walk in their shoes," Ross says. "They saw the worth in one another, and it allowed them to find the strength and courage to compete and fight back. I don't just want the audience to know it, I want them to feel what that means. If I've done that, I've succeeded. Time will tell."