For six weeks this past winter, the filly Genuine Risk took her ease on the 2,000 acres of heaven called Catoctin Stud, the Firestone farm four miles west of Leesburg. She walked the rolling hills behind miles of blackwood fencing. "She relaxed here, and then we sent her to Florida to race," Bert Firestone said.

Now the most famous female runner this side of Rosie Ruiz, Genuine Risk won the Kentucky Derby 10 days ago. She will try the Preakness Stakes this Saturday at Pimlico. If all goes well there, she'll go in the Belmont at New York three weeks later.

"The toughest race will be the Preakness because it's a sixteenth of a mile shorter than the Derby," Firestone said. The Preakness is 1 3/16 miles, the Belmont 1 1/2 miles. "If I had to say which race worried me the most, the Preakness or the Belmont, I'd say the Preakness. She's bred for the mile and a half."

Not that the master of Catoctin Stud is much worried about anything these days. Bert Firestone is the most happy fella. Forty years after his dad paid a quarter to put him on a pony ride . . . 25 years since he quit college to chase horses . . .a dozen years after he bought his first thoroughbred with $20,000 earned in a business he built by himself . . . right not Bert Firestone has a fulltime job just trying to quit smiling.

Well, yes, a Triple Crown would be nice, but Firestone doesn't need it.

"Whatever Genuine Risk does now, she has already won the greatest race in the world," he said.

"Friends call up and people write letters and people you don't know come up to congratulate you -- and they don't know races. They don't know the Arc de Triomphe, they don't know the 2,000 Guineas. The only race they know is the Kentucky Derby. It is the greatest race, and so we've had a really good year whatever happens now."

Racing is a high-risk game. If Bert Firestone on first meeting seems shy and diffident, it is safe to say the first impression is misleading.At 48, he has by his own craft and guile built a multi-million-dollar construction firm from the ground up. He is not of the Firestone family.

He worked not with tires but with dreams. As gorgeous as a horse farm is with beautiful animals at play on green velvet meadows, the farm yet is a dark gamble with high stakes. No shy, diffident people succeed here.

Bert Firestone owns 2,000 acres an hour's drive from the White House. He owns two more farms in Ireland, both purchased from Aga Khan. Of his 120 thoroughbreds, perhaps a third are in training and will make 400 starts this years. Those colts and fillies that don't come up to his standards -- they must be able to win a stakes -- -- are sold off to reduce the $40-a-day expense they cost.

Catoctin Stud is a racing factory. As surely as A. J. Foyt builds Indianapolis 500 racers, Bert and Diana Firestone oversee the creation of thoroughbreds made to run in the classic events. Thirty people work full time at Catoctin , some of them living in the 11 houses on the farm. They have 250 head of cattle there, they grow corn, they grow wheat. Firestone bought the place seven years ago, two years after buying the first Aga Khan farm in Ireland.

The next year, he married Diana, whose father owns the Johnson & Johnson bandage company. She had a successful thoroughbred breeding farm of her own.

"We merged businesses," Bert Firestone said, smiling. It is the second marriage for each. They have one child by this marriage, three each from their first marriages.

Firestone still runs his construction business that deals mostly in building warehouses and industrial parks. But he spends "99 percent of my time with the horses. My first love is the horses. We are in business we love."

In this high-risk business, Bert and Diana Firestone took a chance 10 days ago. No filly had run in the Derby in 21 years; only one ever won it, that one 65 years ago. And here came the Firestones -- relative Johnny-come-latelies in the stuffy world of thoroughbreds, what with barely five years at the highest levels of racing -- and they were going to run a filly in the world's greatest race.

"We stuck our neck out," Firestone said.

The beginnings of a smile played across his face.

Now came the full smile. A smile 2,000 acres wide. Trumpets, drums, 76 trombones and a Shriner's parade through his farm office couldn't have made Bert Firestone smile the way this filly Genuine Risk has.

With good reason. The filly is the ultimate product of hard work. Some romantics (blush) would speak of Genuine Risk in the same sentence with Rosie Ruiz, rendering the animal human and therefore (the blush runs deeper now) more lovable. We know, too, that the Firestones' 16-year-old son, Matthew, did the bidding on the filly at a yearling sale.

This makes a good story: The kid, 14, buys a girl horse that wins the Derby. Sounds like a cript for a Shawn Shaun Cassidy TV episode. All it needs is Kristy McNichol as the jockey.

Truth is better. At age 7, Matthew Firestone was going to horse sales with his father. ("Matthew set up a shoe-shining business at Saratoga when he was 7, and he charged, I think, according to how much you could pay. He came home with a pot full of money every night.") The kid knew a horse when he saw one, then, and he saw this filly two years ago.

"Matthew told us about her and said he had this horse he wanted us to look at," Firestone said. "We all checked her and she was a nice filly. He knew what he was doing. It wasn't like here was a kid spending Dad's money just to be spending it."

Right after Matthew's purchase of the filly for $32,000 -- $3,000 under his father's limit -- Bert Firestone did something that will give his son a nice start in the breeding business.

"I told Matthew, Chris and Lorna (three of the Firestones' seven children) that they could have the filly as their first broodmare," Firestone said.

Breeding a Derby winner to a Derby winner has never been done. The Firestones, after Genuine Risk's 4-year-old racing campaign, have in mind breeding dates with Spectacular Bid and Honest Pleasure.

Honest Pleasure was Firestone's first big horse. He paid $45,000 for him. The odds-on favorite in the 1976 Kentucky Derby, Honest Pleasure seemed so superior "all he had to do was run around the race track and he'd win."

It is a high-risk game. Angel Cordero, riding Bold Forbes, took a six-length lead early. Honest Pleasure never caught up, finishing second. "It was my biggest disappointment in racing," Firestone said.

Last May, another Firestone colt, General Assembly, ran second in the Derby, too, trailing Spectacular Bid.

These hurt.

It was nice that business was good. The son of a New Jersey real estate man. Firestone studied business at the University of Maryland and Virginia until "the horses got the best of me." He was a real estate broker before starting up his construction business. It was nice that Honest Pleasure and the wonderful filly Optimistic Gal cost Firestone only $100,000 at the sales and won $1.5 million racing. Nice for business: Firestone owns 46 broodmares, three stallions and shares in 33 stallions such as Secretariat, Spectacular Bid and Sir Ivor.

But it hurt to lose. It hurt to lose the world's greatest race twice. "You are in it for the winning," Firestone said.

Not for the glamour. The Firestones are private people, seldom seen except by close friends. Cocktail parties are Bert Firestone's idea of everlasting pain. "Everybody's kowtowing to everybody, trying to make you feel good," he said.

If you're in racing, Firestone says, you're in to win and you work at winning. You find the right yearlings, you break them right (the Firestones, both expert riders, have helped break their runners), you hire the best trainer in America (LeRoy Jolley: and then you try not to offend the gods of racing.

"In '76, when Honest Pleasure ran, the people at Churchill Downs showed up -- early in the week -- how to get to the winner's circle in Derby Day," Firestone said.

"This year I told them, "I don't want to know how to get there. We'll find our way if we have to.'"

Firestone smiled trumpets and trombones again.