Serena Williams fell to her knees, throwing her head back with eyes closed, fists clenched and mouth open in partial smile. Her expression was of gratitude, exhilaration and maybe a little disbelief. She’d out-powered the reigning champion, her older sister Venus, in straight sets to take the 2009 Wimbledon Ladies Singles Championship.

Embracing at the net, Venus appeared exhausted, her knee bandaged from an earlier injury. But the victory couldn’t have been sweeter for 27-year-old Serena, who had lost to Venus in the 2008 Wimbledon Finals. Hours later, the sisters partnered to win their fourth Ladies Doubles Championship.

Powerful, quick and agile, Serena Williams thrives on winning. Since her Wimbledon loss last year, when she was less than gracious in a televised question-and- answer session, she says she’s worked on being a better loser (although she hasn’t had much opportunity to practice the skill lately). “I used to be really, really bad and very unprofessional after a loss because I hate losing so much,” she tells SUCCESS in an interview days after winning this year’s championship. “But I’ve come to realize that a loss is not the end of the world. I don’t cry as much. I realize I can’t win everything.

“But don’t think it doesn’t hurt. I’m just learning not to show it,” she says. “I don’t like it, and what I do is go home and practice harder. I work harder. I train harder. When I step on that practice court in the days after a loss, I have an anger in me. It is subconscious. I don’t mean to be that way. But now I use that anger to make me better. It propels me to work harder.”

Since last year’s loss to Venus, Serena has won three of the last four Grand Slam tennis tournaments, “and I should have won the French Open, too,” she says without any hesitation. And with about $24 million earned in her career, she’s won more prize money than any female athlete in history.

Many Open Doors
“I have always been a perfectionist,” she says. “When I was 5 years old and in kindergarten, we had a project due and I was up late working on it, so late that my mom had to force me to go to bed. But I kept getting back up because I wanted to re-do the project until it was 100 percent perfect. Eventually, I fell asleep and didn’t get it done because I wanted it to be perfect more than I wanted to just get it done.”

Unlike that childhood experience, Williams’ perfectionism today doesn’t seem to thwart her in reaching her goals. Ranked as the world’s second-best player, she has won 11 career Grand Slams and become recognized as one of the game’s all-time greats, a stage she gladly shares with Venus.

Seeing the intensity and power she brings to the game, it’s hard to imagine her being anything but single-minded in pursuing tennis. But Serena Williams has other passions, too. In fact, there doesn’t seem to be enough time in the day, week or month for one of the world’s most gifted athletes to chase her many interests. When Serena does decide to walk away from tennis, triumphantly closing one door, what door will she open next? More accurately, what doors will she charge through?

Will it be the fashion world? Her designs have graced several runways, and she’s modeled her designs and others, including swimsuits for Sports Illustrated.

Or will it be in Hollywood as an actress or writer? Having starred in a reality show and done appearances on ER and My Wife and Kids, Serena is writing a TV show storyline she hopes to share with Hollywood friends next year.

Don’t exclude family life, either. Serena wants to be happily married with children by her mid-30s.

And she’s also creating a philanthropic legacy, with pet causes including at-risk children, ovarian cancer research, the Special Olympics and the newly opened Serena Williams Secondary School in Kenya. Serena says she wants to use all her talents and skills to make a difference for others, and says her role models include Oprah Winfrey. In fact, she reluctantly admits being the next Oprah Winfrey wouldn’t be bad either. “Who wouldn’t want to be?” she says, laughing.

Although some have criticized her off-the-court interests as potential distractions from tennis, Serena says her other vocations probably made her a better player, particularly attending design school when she was younger, which stimulated her mind and creativity.

Against the Odds
Born in 1981 to Richard Williams and Oracene Price, Serena was the baby of five sisters, three of them from Oracene’s previous marriage. Encouraged by their father, Venus and Serena were very young when they started John Russo/Corbis Outline playing tennis on the public courts of their childhood hometown of Compton, a Los Angeles suburb better known for crime than country clubs. When Serena was 9, the family moved to West Palm Beach, Fla., for better coaching and opportunities to play highercaliber players. Serena started playing professional tennis in 1995, a year after Venus turned pro, and won her first professional singles title in 1999.

As a teen, Serena didn’t pay much attention to clothes. “I always left fashion up to Venus and everyone else who really had style,” she says. But Serena always found herself drawing outfits on scraps of paper. She sketched designs on long plane trips and between tournaments. With a polite nudge from Venus, who after high school enrolled in college courses at The Art Institute of Fort Lauderdale, Serena followed “Big Sis” and enrolled in the same school.

“Instead of playing tennis, watching television, playing tennis, watching television, I accidently found a new place for my creative energy,” Serena says. “Honestly, I think I would have been an average tennis player if I hadn’t gone to school. I was wasting away watching television. School was work, but it was fun.”

Serena studied fashion design, spending most of her course time sewing and drawing, learning the construction of garments and gaining an understanding of the manufacturing end of the design business. “I know design. I love design. I know how to make patterns work. It’s just something that I love and it’s something I developed a real, deep appreciation for,” she says.

Meantime, Venus also pursued careers in fashion and interior design, developing her own EleVen clothing line and opening her own V Starr Interiors design company in Florida.

Coming into Her Own
Although Serena had been influenced by her sister in many ways, including fashion, she says fashion also allowed her to make a personal statement. She started developing her own style with adventurous, eccentric and fun outfits. (Who can forget the black Lycra catsuit she wore in the 2002 U.S. Open or the white trench coat worn at Wimbledon this year and last?) In her book On the Line, scheduled for release in September, she explains how fashion also helped her in tennis, as she realized that presenting her best image on the court helped project a positive picture to the world.

Serena debuted her Aneres clothing line in 2003 and premiered her Aneres Clothing Collection the following year. Coming up with the name, which is Serena spelled backward, was an empowering moment. “I was like, ‘Wow, I can pronounce it and it doesn’t sound stupid,” she laughs. “I knew then I could chase my dreams outside of tennis, be it my clothing company, jewelry, a production company— there are so many neat and wonderful things out there.”

At one point, Serena had a line of tennis clothing with Puma and now has a line with Nike thanks to a deal signed in 2004 worth $40 million that allows her to work alongside the company’s development team. At Wimbledon this summer, Nike remastered the trench coat for her to wear during warm-ups and to walk on and off the court. The feminine white court dress she wore also was from Nike.

“I am so lucky. Being a tennis player, every tournament I play gives me a great opportunity to market whatever I am working on or wearing,” Serena says. “It gives me the platform that allows people to see it firsthand and allows them to make a decision on whether they like it or not. I want people to feel confident that if they are buying an item from Nike or a product that I designed or represent, it’s a good product because you associate it with me.”

Bucking the Critics
Serena is selling her active wear fashion line in boutiques in Miami and Los Angeles. Last April, she made the leap to infomercials on the Home Shopping Network when she launched a signature collection of everyday dresses, tops, handbags and jewelry. Scheduled to return to HSN in September and November, Serena says the items priced at $100 or less immediately connected with consumers.

“I felt so honored that everyone wanted to try them and wear them,” she says. “Being an athlete, I only have to satisfy myself. If I go on the court and either win or lose, it’s only about me. But being a designer, I really want to make people happy and I want them to be happy with what I make.”

Some in tennis would disagree with Serena’s assessment, saying her athletic talent conveys greater obligations. Tennis legends Martina Navratilova and Chris Evert have said they don’t believe Serena can reach her potential when her commitments are strung out like a volley being played from all corners of the court.

“Serena is designing dresses, and I feel she wants to be an actress more than a tennis player,” Navratilova said in a 2007 interview.

Evert was more direct, much like an overhead slam at the net. “In the short term, you may be happy with the various things going on in your life, but I wonder whether 20 years from now you might reflect on your career and regret not putting 100 percent of yourself into tennis,” Evert wrote to Serena in an open letter three years ago. “Because whether you want to admit it or not, these distractions are tarnishing your legacy.”

Tennis First
If Serena has been distracted, her record doesn’t show it. Earlier this year, she declared herself the world’s best player, even though Dinara Safina was ranked No. 1. And Serena’s record backs up her bravado; ranked No. 1 in the world by the Women’s Tennis Association on four separate occasions, she’s the only active female player to have won all four Grand Slam tournaments during her career— one French Open, three Wimbledon, four Australian and three U.S. Opens.

Serena says she’s not bothered by Evert’s and Navratilova’s critical evaluations of her career, or by others who have hinted she’s spread herself too thin or that her goals outside of tennis are unreasonable. “I think everyone is entitled to their opinion, and they truly might think that I don’t need to do all these other things,” she says. “Honestly, I am honored that they are even concerned about how I am playing. I mean, hey, they really want me to do well. I just think when you are given a great opportunity and you have the chance to do other things, you need to follow your dreams and try to make the most of your opportunities.”

Serena doesn’t even read her own press, she says, although she does have a scrapbook full of articles, “and I plan to go back and read them once I’ve stopped playing. I don’t play for [writers or critics], and I don’t want their opinions impacting me now.”

And at the front of the line right now, Serena says, is her first love, tennis. Serena Williams knows that results on the court define her as a tennis player. Although she may not have the time to concentrate on her outside interests as much as she’d like, that day will eventually come. And Serena will be ready.

“I don’t really care whether my stuff is [financially] successful, I just want people to like it,” she says.

“I am not doing anything for money. I am doing it because I love it. Anyone who knows me knows that I live a simple life and enjoy the simple pleasures of being happy and making people happy. That’s really what all this is about.”

Don Yaeger is a New York Times best-selling author, former Sports Illustrated associate editor and award-winning speaker.