FRANCE'S MARIE SARA BOURSEILLER seemed destined from birth for a career in show business or the arts. Her father, Antoine, 60, is director of the opera in Nancy. Her late mother, Chantal Darget, was an actress at the Comédie-Française in Paris. Her brother, Christophe, 34, is an actor, and sister Rosalie, 33, designs costumes. Film director Jean-Luc Godard (Breathless) is her godfather and actress Daniele Delorme (Gigi) her godmother. "I was raised near the stage and knew that I'd be performing something somewhere," says Marie Sara.

She was right about that—but it's doubtful that anyone in her family, herself included, knew what kind of performing it would be. At 27, Bourseiller is the only woman in the ranks of rejoneadores—horseback bullfighters—and one of the best of either sex. "It is a ritual, an art, a ballet consisting of the horse, myself and the bull," says Bourseiller, who, like all rejoneadores in France, Spain, Portugal and Latin America, fights from horseback in a prescribed style, riding three mounts in turn for each bull. "The key is my relationship with the horse, because we must be one to move toward or escape from the charging bull."

Fighting from the saddle is safer than fighting from the ground, and the bulls' horns are slightly blunted and covered with leather socks. But the bulls still weigh half a ton, and neither horse nor rider wears protective padding. Over the years, Bourseiller has fallen from her horse but has escaped serious injury. "I worry every time she fights," says her father, Antoine. Adds Simon Casas, 44, a retired matador who has been Bourseiller's lover and mentor for the past decade: "I'm too scared to talk about how scared I am. She's my woman and not just another performer."

The Paris-born Marie Sara saw her first bullfight while vacationing in the Camargue region of southern France when she was 13. She decided on the spot that the sport was for her. "I was surprised but not shocked," recalls her remarkably understanding papa. "She wanted to be in a field where she could excel without competing with the rest of the family. I've tried to help her to the maximum, and my friends originally put her in touch with Simon Casas, though none of us knew when she was 15 that she'd wind up living with him."

"I saw that she was beautiful, and it was lust at first sight," Casas confesses now. "She knew nothing about horses or bulls. She didn't even know how to ride. But it didn't take me long to realize she had all the qualities of a champion—passion, patience, intelligence, the ability to work hard." Under Casas' tutelage, Bourseiller trained for six years before her public debut in 1984. Today she is often compared to the legendary Conchita Cintron, acclaimed as the greatest female bullfighter of all time and now living in honored retirement in Portugal.

Cintron and Bourseiller aside, women are rareties in a sport steeped in macho myths of strength and courage. "I never thought of competing with men just because I'm a woman," says Bourseiller, who habitually wears makeup and jewelry even in the bullring. "Men in this business respect my professionalism. Women are either very curious, admire what I do or think I've completely lost my mind."

As for another area of controversy, she acknowledges that bullfighting is repugnant to animal-rights groups and to many others who are outside the traditions of Mediterranean culture. Personally, she says, "I would drive an hour out of my way to avoid seeing an automobile accident and wouldn't kill a fly. But in the ring I find the death of the bull very abstract and a necessary part of the spectacle. There is simply no other denouement, and it's nothing to be ashamed of. I've given up arguing about it."

In any case, bullfighting is definitely not a sport to grow old in; retirement before 30 is common. For the moment, though, Bourseiller, who works on contract at between $5,000 and $20,000 a fight and has already fought 30 times this year, says she is "too involved in what I'm doing to plan for the future." She has trademarked the name Marie Sara—as she is universally known to fans—and "might design clothes for women who want the outdoor cowgirl look," she says. "I also want to raise a family, and I consider it a good omen that Conchita had six kids after she retired." So when might Bourseiller emulate her esteemed predecessor? "Marie Sara will stop," predicts Simon Casas, "when she has received the recognition in the bullfighting world—the press and aficionados—that she has reached the top. One sign that she is almost there came recently when Conchita Cintron officially recognized Marie Sara as her successor.