ASCOT, England -- Impeccably attired in top hat and tails, he stood chatting in the spacious backyard at posh Ascot Racecourse. Yet his smile seemed forced and his eyes lacked sparkle. Although he looked like the height of fashion, Gary Stevens was feeling pretty low. He was all dressed up with nothing much to do.

That was three years ago, about six months after chronic knee pain became so unbearable that he quit riding, which had made his name and his fortune.

"In 2000, I didn't realize I looked so unhappy, but everybody I knew said that I did, and I was unhappy," Stevens said Saturday at Ascot. "I was the racing manager for The Thoroughbred Corporation and I was at Royal Ascot, which was great. But I was only 36 when I retired, and I still should have been doing what I wanted to do."

Stevens could smile as he reflected on that rough patch in his life, because that sunny afternoon, he would have four mounts on the final card of the five-day royal meeting. Thanks to joint medication, arthroscopic surgery and therapy, Stevens is riding pain-free for the first time in almost 10 years. He's been in world-class form since returning to the saddle in the fall of 2000, and not only has his old career been reborn, he's also found a new one as an actor. He has a featured role in the upcoming movie "Seabiscuit," which is based on Laura Hillenbrand's best seller and has all the makings of a box-office smash.

The 40-year-old native of Idaho plays George Woolf, who fills in for the injured Red Pollard, played by Tobey Maguire, and rides Seabiscuit to victory over War Admiral in the film's climactic sequence, the famed 1938 match race in the Pimlico Special. Jeff Bridges is cast as Seabiscuit's owner, Charles Howard, and Chris Cooper is his trainer, Silent Tom Smith. It opens July 25 in North America.

Though Stevens never had acted, for many years he'd felt a kinship with Woolf, a memorable figure whose passion for telling the truth was as remarkable as his horsemanship. "The Iceman" was only 36 when he died in 1946 after a spill at Santa Anita, where a statue of him stands in the walking ring. Each year racing writers vote to present the George Woolf Memorial Award to the jockey who has been a credit to his profession. Stevens won it in 1996, one of his top honors in a Hall of Fame career.

Admiring someone is one thing, but could he bring back to life on the big screen a man who died 17 years before he was born? Stevens wasn't sure.

"I was very intimidated by the idea of acting, to say the least," he said. "But what made me feel more comfortable was that I was a fan of George Woolf. I had my 25th birthday party in his old apartment above the Derby Restaurant [near Santa Anita], and I really felt like I knew the guy."

To prepare Stevens for his first role, the film's producers sent Stevens to Palo Alto, Calif., to work with Larry Moss, the acting coach for Maguire and Tom Hanks. The plan was for Moss to counsel the rookie in three five-hour sessions to see how much work would be needed. Yeah, the articulate, handsome athlete looks the part, but can he play it?

"The first night, we just sat and talked," Stevens said. "The next night, we read through the script together. I hadn't gone through it before with anyone, just read it by myself.

"Halfway through the script, Larry was very pleased and he told me, 'You're ready.' ''

Even after being called a natural by a show-biz expert, Stevens still was edgy. So was the star, Maguire, though for different reasons. After bulking up for the title role in "Spiderman," the 5-8 Maguire wondered how he ever could look like the scrawny, battered Pollard.

"Toby held up a picture of Pollard and said to me, 'I don't look anything like this guy,' " Stevens said. "I told him, 'Don't worry, you will.' After Tobey lost 28 pounds, his eyes were sunken back in his head and he looked like Pollard did.

"The real hard part for him was gaining back the weight quickly because they started shooting 'Spiderman II' six weeks after we finished 'Seabiscuit.' "

Stevens and Maguire became close as they helped fill in each other's gaps. "Tobey was intimidated by the riding scenes, and I was intimidated by the acting scenes," Stevens said. "I was able to give him confidence, and he was able to do the same for me."

While in England recently, Stevens enjoyed a working vacation as he and his English wife, Nicola, visited her family. "You can't beat Royal Ascot," Stevens said. "It's by far the most enjoyable and exclusive race meeting in the world. To me, this is the ultimate in world horse racing."

In Wednesday's opener he brought in his fourth Royal Ascot winner, and his first since 1999, 20-1 shot Membership. Two days later, Stevens narrowly missed his fifth. Trainer Clive Brittain told him to hold up Membership as long as he could before coming with a late run, and Stevens delivered a shrewd, waiting ride in the style of his idol Woolf.

"When I saw Gary was available, I clapped my hands," said Brittain, an old-school guy who's won major stakes all over the world. "Here is a jockey with a racing brain and timing . He's a class act, isn't he?"

A therapy program designed by Joe Horrigan, the trainer for the National Hockey League's Los Angeles Kings, has helped Stevens stay fit. He accepts fewer mounts these days, by choice rather than as a concession to discomfort. His success allows him to be very selective, and he's been getting on only two or three a day during the week at the current Hollywood Park meeting, where the quality of racing has been down. On weekends, he often flies to New York to compete at Belmont Park.

"I don't mind riding six or seven a day if they're good horses," Stevens said. "If this acting career keeps up and I can mix some riding with some filming, that would be great."