08/04/2003 at 01:00 AM EDT
Every superhero needs a secret identity. Fresh off the smash success of Spider-Man
, Tobey Maguire tested his out last September at the Del Mar Thoroughbred Club in Del Mar, Calif., as he anonymously soaked up the atmosphere while researching for his horseracing drama Seabiscuit
. "In our world, people were more interested in betting on horses than in Tobey Maguire," says jockey Gary Stevens, a Seabiscuit
costar. "I really think he enjoyed that."
It was a rare quiet day for Maguire, in the spotlight since last summer's Spider-Man grossed $404 million at the box office. Now, eager to prove that he's more than a web-slinger,
Maguire, 28, is tackling another famous figure—half-blind, too-tall jockey Red Pollard—in Seabiscuit
. He had little trouble identifying with the role. "Red Pollard was a brawling boxer who carried Emerson and Shakespeare in his pocket," says director Gary Ross. "That's Tobey—he is those contradictions. I've never met a sharper person." Or a more focused one. To prepare for the film, Maguire, who pocketed an estimated $12 million paycheck, installed an Equicizer—a racehorse simulator—in his $3.5 million Beverly Hills home, and whittled 20 lbs. off his 160-lb. frame. "I didn't realize what kind of athletes jockeys are," Maguire says. "The first time I got up in the stirrups and did a bit of a gallop on a racehorse, after a couple of minutes my legs were noodles. I could barely stand up."
He's taking good care of himself socially as well. After partying hard in his teens, Maguire has been sober since 19. (His chief vice these days: Cuban cigars.) And he's "blissfully in love," says Ross, with a low-profile steady: Jennifer Meyer, 26, his girlfriend since early this year. "They both are similar because they are very guarded around people they don't know," a friend says of Meyer, the daughter of Vivendi Universal Entertainment CEO Ron Meyer. The two spent July 4 at a Malibu beach party with Maguire's longtime friend Leonardo DiCaprio
, but Meyer seems most content by Maguire's side at L.A. Lakers games and on movie sets. Says a pal: "She's not a scenester."
It's a stability that was missing from Maguire's childhood. His parents, cook Vincent and secretary Wendy, split when he was 2, and Maguire moved frequently. Unbeknownst to him, he was preparing for Seabiscuit
even then, attending horse races at Del Mar. "I used to go with my family," he says. "To me it was just a great show."
With his career thriving (he's taking home $17 million for Spider-Man 2
, now shooting in L.A.), Maguire—whose star rose with brainy turns in 1997's The Ice Storm
and 1999's The Cider House Rules
—won't take his own brood to the races for quite some time. "I'll wait until I'm in my 30s to have kids," he told Playboy. But children are already a big part of Spider-Man's life. "Any time there's a little kid even remotely in the area," says Seabiscuit costar Elizabeth Banks, "they're craning their neck to get a look at Tobey."
Julie Jordan, Kwala Mandel and Rachel Biermann in Los Angeles