Jumpsuit, Hermès (price on request). The Shops at Fairfax Square, 703-506-4546. Bra, Eres ($310). Jaryam, 1631 Wisconsin Ave. NW, 202-333-6886.

Anna Kournikova is talking about her butt. It kind of takes me by surprise since up to now our phone call's been all polite, cocktail party-style chitchat. In the 10 minutes we've been talking I've discovered we both love to be out on the water (I sail, she motors), adore dogs and try to stick to a workout routine.

"I just work out a couple hours a day, I try not to do too much," she says, casually, making me feel pretty lame for what I call exercise most mornings. "I usually spend an hour playing tennis, do an hour on the elliptical or treadmill and then I go to the gym to do weights and squats and lunges… to keep [my] lower body tight and firm."

This is when I remember that the 28-year-old Russian-born tennis star on the other end of the phone once sent the sports world into a sexualized frenzy. Kournikova's first US Open in 1996 at age 15 sent photos blazing across the Internet as soon as she hit the courts. She drew complaints—largely from women—that she was becoming famous for her smokin' hot body, long blonde hair and enchanting grin rather than her tennis skills. (In Texas Hold 'Em, an Ace-King hand has been dubbed the "Anna Kournikova" because it looks good but seldom wins. Ouch.)

But Anna strode through the grousing, posing for Sports Illustrated and Maxim even as she became known for her foot speed and aggressive play on the baseline, taking home 16 doubles championships and two Australian Opens. At her peak, she was ranked eighth in the world in singles, and number one in doubles.

She played so hard that her body still craves the intensity. "I need to do double the workout of the normal person," she confides. "My body is used to doing something really hard, so if I do something easy, it's nothing for it, it doesn't really react." I thank her for making me feel like my fitness routine is a little more normal—after all, I'm no professional athlete.

And neither, anymore, is Kournikova. She stopped playing tennis in 2003 after a string of injuries eroded her standing. "I don't miss the grind of it, being in a hotel room 10 months out of the year, always packing and unpacking. But back then I didn't mind it, I was so young." She was beyond young, actually. A child phenom, she left Russia at age nine to start training with übercoach Nick Bollettieri in Florida.

Almost 20 years later, what she does still miss is the competition. "I miss the adrenaline. Playing a night match at the US Open under the lights in front of 10,000 people. Tennis gave me a life," she says, and then catches herself. "Tennis is still my life, I loved the sport." As she slips into past tense again, I wonder if it's because her English gets choppy when she gets excited, or if it's more Freudian. Tennis is still her thing—she plays World Team Tennis for the St. Louis Aces—but she's increasingly devoting herself to international humanitarian work.

Giving Back

Kournikova has been quietly flying to Haiti and Russia to work with those in need. She's talked with child slaves about their plight; she's handed out condoms; she's gotten AIDS tests to set an example for sex workers who often fear testing and the stigma associated with it and the disease itself.

"A few years ago she was kind enough to attend our YouthAIDS gala in DC," says Marshall Stowell, director of communications for PSI (formerly known as Population Services International). The group focuses on improving the health of poor and vulnerable people in the developing world. "She came up to me after listening to Ashley Judd and Bob Geldof speak. She explained that she grew up in Russia in a one-room apartment with no running water. She told me she knew what it was like to struggle, and she wanted to help."

Stowell invited the athlete to join PSI's trips to Haiti and then Russia. While overseas, he discovered that his newest celebrity advocate likes to get her hands dirty. Literally. "In one Haitian village, the community was so poor that the children ate cookies made of mud—mud, a little lard and a little sugar—just to fill their bellies," he recalls. To his dismay, Kournikova walked right up to the woman selling them.

"Marshall wouldn't let me buy a mud cookie," she says, still sounding a bit aggrieved. "I asked him for some Haitian money, and he was like, ‘Nope.' But if [others] eat them, what can happen to me?"

The PSI team also found that she has an uncommon ability to connect with people in hopeless situations. Kournikova says she still shivers when thinking of the young woman she met at a mobile outreach center for homeless kids in St. Petersburg. Just 22, she looked more like a 35-year-old woman, and she'd already given birth to four children. One had died, another was placed in an orphanage when she became sick. "She told us that when her baby was taken away from her, she didn't want to live anymore," Kournikova says. "She was living on the streets, and coming to the shelter to get food and diapers. She looked like she had completely lost hope. It's just devastating to think that she's in Russia where it's freezing, and she's on the street with a two-year-old and a newborn."

Every night during the weeklong trip, Kournikova ate with the PSI team. The day they met that mother, it was a very quiet dinner. "We were all thinking how to sneak that girl home in our luggage, to bring her back with us."

Upping Her Game

Compared to the tennis diva Anna Kournikova of the '90s, this Anna is practically a Capitol Hill wonk. "PSI's work is very numbered. They actually calculate how many lives they helped save last year, how many pregnancies they were able to prevent, how many families received and learned how to use malaria nets. In Haiti, one net can save a family of five for two years. Imagine that—five people, one net. And we document every family that gets a net, and how many more families in their village need one."

Kournikova is approaching her humanitarian work quietly, with no melodrama or paparazzi. Instead, during those morning elliptical sessions, she studies reports on malaria, child survival, HIV and reproductive health.

She used a similar process when she approached the Boys & Girls Clubs of America. Starting out by talking to small groups of children about living healthy lifestyles, she slowly taught herself to play on this very new style of court. Instead of studying opponents' moves, she was now memorizing obesity rates. Eventually, she graduated to wooing donors during fancy dinners.

"It's great if you just show up," Kournikova says, "but if you really want to do something, you need to know what you're talking about."

She's from the George Clooney school of celebrity humanitarianism, spending time in a country and learning the ropes before stepping in front of a microphone. Kournikova penned an 11-page report for Oprah's website about her experiences in her home country, but her work has otherwise been pretty under-the-radar. At some point, locals may see her in town when she visits Capitol Hill to talk about HIV prevention and anti-malaria efforts. But not any time soon. "I hope some day I'll be ready for [Congressional testimony], but I don't feel like I'm educated enough yet to talk on such a large scale," she says. "If you read a book you get all the facts and statistics, but if you see with your own eyes, it really changes your whole understanding."

"What I saw in Haiti was just ridiculous," she continues. "[When] I spent summers in the [Russian] countryside with my great-grandmother, running around barefoot, at least we had water, we had fields, we could grow food."

"And you weren't eating mud cookies," I say.

"Exactly, there you go," she says, trilling her r's just a bit. "You have to experience their life. We are there in their village, in their homes, and I want them to feel comfortable. I want to show them we're all the same."