Venus Williams stands in a torn-up condominium in Palm Beach, Fla., assessing a man's shower curtain. The condo has the mausoleum feel of a work in progress, with unpainted walls, freshly marbled floors and furniture draped in drop cloths. Contractors mill about expectantly. Against this stark monochrome, Williams is an arresting, 6-foot-1 presence, dressed in a denim skirt and a leopard-print Versace top that fits like a second skin, the striated muscles of her back rippling and rearranging themselves as she lifts a swatch of shower curtain to the light. The curtain itself is a notch above ordinary -- a scrap of fawn-colored linen -- but the way the 22-year-old Williams studies it, you'd think it was the key to some faraway kingdom, a piece of a large and scintillating puzzle. The question at hand is whether this fabric matches the yachty style of the recently divorced, retired manufacturing exec who hired the tennis star to decorate his place.

''Hmmmmm,'' Williams says. The contractors pause to listen. Her client, a deeply tanned man wearing a peach Polo shirt and tasseled loafers, leans in close. So far, Williams has mulled over a set of earth-tone faux finishes for his wall, determining one to be ''too yellow'' and another ''too glossy.'' She has torn the plastic shipping wrap off her client's old couch and scrutinized its battle-scarred green leather. Now she clomps in her Fendi heels into the man's bathroom, checking the swatch against the shower tiles before uttering her final pronouncement in a voice both soft and self-assured: ''Seems to me this'll work just fine.''

In November, after losing in the semifinal round of the Women's Tennis Association Championships to Kim Clijsters, the elder Williams sister donned an ivory silk strapless dress and held a press conference to announce that she was starting a Florida-based interior-design firm called V Starr Interiors. (Her full name is Venus Ebony Starr Williams.) She posed for photographers before an elegantly arranged furniture display in a showroom in Los Angeles, where the championships had been held, saying she intended to run her new company without missing a beat in her tennis career. To this end, she has rented an office and hired an employee -- a Boca Raton designer named Bonnie Nathan -- and says she hopes that the strength of her celebrity will pull in upscale clientele. According to Nathan, V Starr has exactly ''two and a half'' clients, the biggest being the manufacturing exec, a tennis enthusiast who appears both humbled and titillated by Venus Williams's presence in his home.

''How's your game coming?'' Williams asks. And when her client mentions that he has been struggling with an injury, she offers a collegial smile. ''Yeah, my calf's been bothering me, too.''

Williams's business announcement was picked up in newspapers from Scotland to Thailand, and almost immediately, back at V Starr's small offices in Palm Beach Gardens, the phone started to ring. On the day I visit, two weeks after the press conference, Nathan is still sifting through the pileup of messages. But if the start-up of V Starr has been properly high-profile, it has also led to a flurry of speculation that the formerly indomitable Venus might be edging toward retirement, having been soundly spanked by her younger sister in the finals of the French Open, Wimbledon and the United States Open last year.

In postmatch interviews last season, Venus, who has won four Grand Slam titles and $11.9 million in prize money, regularly complained of fatigue, hinting that she was looking for a life beyond tennis. This is unusual talk in the tennis world, a place where top players like Williams generate a hierarchical swirl of agents and trainers, hitting partners and reporters, all crisscrossing the globe over the course of a grueling 10-month season. Tennis creates its own weather, which is to say that for many, there is no life beyond tennis.

Being a Williams, however, means you do things your own way. While other players on the Women's Tennis Association tour compete in an average of 24 tournaments a year, Venus and Serena each played a little more than half that number last year and still remained on top. Together, they have won 8 of the last 13 Grand Slam events. What might seem like hubris to players who compulsively train and compete is what the Williamses like to call ''having a life.'' Serena recently announced that she's trying to break into acting, while Venus has been working on her company's employee handbook -- never mind that there's only one employee.

With this month's Australian Open marking the start of the 2003 season, it's safe to say that all sights are set on ending the Williams family reign. Over the last several years, Venus and Serena have been universally treated as a single organism, as twinned souls embarked on a solo mission -- one that seems to garner a double dose of competitive bile. ''You hear the other players saying, 'We have to keep them out of the finals,' and that kind of thing,'' Venus says. ''They don't think you're listening, but you're there, and you hear stuff.''

It seems the conspirators may have found their opening. According to Rick Macci, who has coached Jennifer Capriati and the Williams sisters at his Florida tennis academy, Venus and Serena's pursuit of outside interests is welcome news to their competitors. ''It's giving other players more confidence,'' he says. ''They finally sense some vulnerability.''

These days Venus and Serena lead increasingly separate lives. From the moment she arrived at last year's U.S. Open dressed in a slinky black cat suit, Serena has made it clear she's comfortable with -- even thrives on -- being a sensation, a platinum blonde and a formidable ball-striker. As the family bombshell, she spent much of the fall traipsing red carpets, accepting honorary awards -- the Associated Press just voted her female athlete of the year -- and working with an acting coach. She has bought an apartment in Los Angeles, often leaving Venus at home in Palm Beach Gardens in the mansion she and Serena built together in 2000 and dubbed La Maison des Soeurs, or house of the sisters.

Lately, Venus says, she has been renting a lot of movies, tending to the family dogs -- Serena has three, including a pit bull named Bambi -- and doing some sewing. Her other sisters (there are five altogether in the Williams family, Serena and Venus being the youngest, and no brothers) often call to check in. ''They say, 'Aren't you lonely?' But I'm not,'' Williams says. ''I'm entertained by my own thoughts.''

Perhaps celebrity has lost some of its luster, or perhaps it's simply that Venus is maturing. Whereas she once drove a Porsche, she now bops around in what she calls her ''monster truck,'' a Toyota 4Runner. Whereas she once boasted of having a shopping addiction, dropping thousands of dollars on designer clothes, she claims -- with a laugh -- to limit herself to buying only ''accessories and hair things.'' Her spending money, she says, is now largely funneled into the interior-design business.

Even her father, the notoriously bombastic Richard Williams, says he won't speculate on Venus's future. ''I used to have a dream for Venus, but I don't anymore,'' he says. ''She's become a beautiful human being who manages on her own.'' It was, of course, Richard who prophesied in 1993 that his daughters, then 12 and 13, would one day be the world's No. 1 and 2 players. And despite the fact that Venus was for years the dominant of the two -- distinguished by a 127-mile-per-hour serve, electric speed and elastic court coverage -- her father proved to be startlingly clairvoyant, having predicted that Serena, with her unparalleled strength, eventually would surpass her older sister.

As Richard Williams's dream finally played itself out last year, with the sisters dueling before record-setting global television audiences, the drama swelled to something more Shakespearean than fairy tale. A happy ending seemed just out of reach. Though professional tennis has produced sets of siblings in the past -- the Everts, the McEnroes -- in each instance, the older child has possessed more talent or birth-order entitlement, facing little or no challenge from the younger. But over the course of the last year, Serena Williams changed all that, slaying her sister's old rivals -- Martina Hingis, Lindsay Davenport, Jennifer Capriati -- on her way to dismantling Venus herself. Whereas in 2001, Serena admitted she had trouble viewing her big sister as the enemy across the net, she evidently got over it. After trouncing Venus at Wimbledon last year, Serena summed up her new mind-set. ''Unfortunately,'' she told reporters, ''it's a war out there.''

The effect was curiously unsettling, akin to watching a princess dethrone a queen, the beta toppling the alpha -- not once, but three times. The play between the two has also been just spotty enough, particularly on Venus's part, to draw armchair psychologists from every corner, postulating that even while Serena has mastered her ambivalence, Venus cannot shed her familial role as her sister's protector -- that when push comes to shove, Serena simply wants it more. ''The way she's dealt with her losses to Serena in the public eye has been first class all the way,'' says Pam Shriver, an ESPN commentator and former player who served as Venus's mentor on the W.T.A. tour for three years. ''What I don't think we know, because Venus has a stoic, private side, is how she handles it behind closed doors, just to herself.'' This year, Shriver says, Venus is ''at a definite crossroads.''

Not only does she begin the season as an underdog, Venus also faces a set of circumstances that could either paralyze or liberate her: the career scripted by her father is now behind her. The sister she has fostered since they were toddlers has come into her own. And her parents, whom Venus acknowledges as the bedrock of her confidence, have recently divorced. The Australian Open presents its own challenge -- playing on Melbourne Park's notoriously gummy hard court, neither sister has ever made it past the semifinals -- and beyond that stretches the long season. If the Williams sisters remain each other's closest competitors, as is expected, they will probably be dogged by the obsessive speculation that followed them through 2002: Are they still best friends? How ever do they manage?

Sprawled in a swivel chair at V Starr's offices, her long legs kicked out in front of her, Williams tells me she intends to reclaim her Grand Slam titles this year. ''I figure once Serena's past the turning point and she's in the position I've been in the past couple of years, then . . . you know, maybe I can do something,'' she says. When I ask whether she's trying to say that it's harder to be the No. 1 player, she bursts out laughing. ''Oh, no, it's much harder to be No. 2, believe me!''

Off the court, Williams has a gentle demeanor -- a low-voiced calm that's leavened by youthful mirth. She speaks primly -- ''Oh, shivers!'' she exclaims when she has messed something up -- and often she will collapse into giggles before she has finished a thought. When her cellphone rings -- at least once every five minutes and usually with a family member on the line -- she hums along merrily with its tones before answering. It's clear that the design business makes her happy. She shows off a stack of vibrant oil paintings she bought from street vendors when in Moscow for a recent tournament. (''I like a lot of color,'' she says.) She points out a wooden chair she picked up in Dubai. (''That used to be an oxcart. Can you believe it?'') When the mail arrives, she pounces on a new set of furniture catalogs, putting a ban on all conversation until she has paged carefully through each one. ''She's deadly serious about the business,'' says Isha Williams, the second of the five Williams sisters and a law student. ''This is not some fly-by-night thing for her.''

Among the Williamses, Venus is uniformly recognized as the family polymath -- the one who, while visiting France, enrolled in French classes, who once stunned a roomful of sports reporters by opining on the Romanov dynasty. When she hits upon a new idea, which seems to be often, she writes it down in painstakingly neat script in the purple notebook she carries with her.

Venus's pace has become something of a hot topic in the constant rotation of cellphone calls between female members of the family. ''My mom called me and said, 'Do you think she's overworking?' She was worried,'' Isha says. ''So then I had to call Venus and say, 'Mom says you should slow down.''' For her part, Venus says she feels no need to slow down. In preparation for Australia, she's been training with a hitting partner in Delray Beach by morning and working on her business in the afternoons. She claims that she has no immediate plans to retire, that she'll leave tennis only when she stops enjoying it. ''Then I'll know it's time to go,'' she says.

The biggest threat to her pleasure, it seems, is not her rivalry with her younger sister but rather the tsunami of hype that builds each time the two meet. When they faced each other in the final round of last year's U.S. Open, Venus confesses, the media chatter finally got to her. ''I couldn't wait till it was done,'' she says. ''I wanted to get away from all the junk. You could be watching a men's match, a women's match or a doubles match, and all they'd talk about was the Williams sisters.'' She does an unflattering imitation of a commentator: '''Do you think it's boring that they're in the finals? Is this bad for tennis?''' She shakes her head like an admonishing schoolmarm. ''Come on now, that's just silly.''

"Silly'' is a word Williams calls up to describe just about anything negative -- a lighthearted deflection of the sometimes relentless criticism lobbed at her and her family. Tabloid rumors that Richard Williams has dictated the outcome of the sisters' matches are silly. Accusations that Venus feigned injury in order to avoid playing Serena in the semifinals of a 2001 tournament at Indian Wells, Calif., are silly. John McEnroe trumpeting that a low-ranked male player could handily beat either Williams sister? Silly. When Lindsay Davenport and Monica Seles whined about how Venus wouldn't say hi to anybody at events? Well, that was silly, too.

Nonetheless, Venus has never quite shed her outsider status in the tennis world, largely because of her family's conscious insularity and the intimidating level of confidence this seems to instill. As Capriati throws hissy fits and Hingis snipes, as losers cry and winners gloat, Venus tends to drift above the sometimes histrionic women's tour with an aloof brand of dignity -- and with Serena trailing demurely just behind. If other players gossip and trash-talk, the Williams sisters practice an even shrewder form of psychological warfare, living in a kind of splendid isolation, barely acknowledging that their opponents exist. Martina Navratilova has criticized them for their lack of humility; McEnroe has called them ''cold as ice.'' Venus understands that others in tennis view her as conceited, but she doesn't worry about dispelling the notion. ''What can I do?'' she says, adding that there aren't a lot of opportunities to get to know one's rivals anyway. ''Everyone's got their own schedule, their own coaches and trainers. It's like a lot of little shows going on, but everyone's separate.''

Any active antagonism from the Williams camp has come from Richard Williams, whose sideline antics are legendary. When the feisty Romanian Irina Spirlea bumped Venus during a changeover in 1997, Venus played down the incident, only to have Richard call Spirlea ''a big tall white turkey.'' After his daughter captured her first Wimbledon title in 2000, Richard rubbed it in with a hand-lettered sign that read ''IT'S VENUS' PARTY AND NO ONE WAS INVITED.''

Times, however, have changed. The Williams parents' divorce seems to signal the start of a more independent era: Richard attends many fewer of his daughters' matches these days, saying he is too busy trying to start a singing career. Venus and Serena more often travel with their mother, Oracene, or one or more of their other sisters. And increasingly they keep their own schedules. Serena, for example, went to Australia weeks ahead of Venus to play in a tune-up tournament. (''I guess she needs the practice,'' Venus shrugs.) For her part, Venus has been working to improve the consistency of her serve, which she hopes will close the gap between her and her sister. ''I want to become like a machine,'' she says half seriously before launching into an Ali-like ham. ''You can't beat this girl! She's too crazy. She's too serious about this game!'' Beneath her swagger, however, lies a yearning for something simpler. ''As an athlete, you work seriously on a time schedule from when you're young, especially if you have someone bringing you up in the sport,'' she says. ''I've been on a time schedule for years. There's a little part of you that says it'll be nice after it's done.''

If Serena begins the new season with an edge, it goes unacknowledged within the family. Isha Williams views her sisters as entering this year ''probably pretty much even.'' And when I ask Richard Williams if he thinks Venus is comfortable being No. 2, he is instantly apoplectic. ''Venus is not No. 2! No. 1 is in your heart and your mind. Venus is No. 1,'' her father says. ''She's always been.''

We are driving through West Palm Beach in Venus's 4Runner, en route to a V Starr appointment, when the official No. 1 phones from Los Angeles. Venus checks the caller ID on her Nokia, turns down the Moby CD she has been listening to and answers, ''Tell me.'' And without formality, they're off at a gallop, picking up the kind of never-ending conversation only sisters can have. ''Did you use the products?'' Venus asks, then waits for an answer. '' . . . But did you try the leave-in conditioner? . . . So which conditioner did you use?'' Serena's voice rises and bubbles audibly over the phone. ''Oh, shivers,'' says Venus, starting to giggle, ''I didn't get that one!''

She pilots her S.U.V. onto South Ocean Boulevard, where palm trees wave languidly in the breeze. ''Eddie George said that?'' Venus practically shouts, beginning to laugh again. She tells Serena about a Richard Gere movie she must rent, before the conversation pinballs back to hair care. ''Girl, you've got to stop yanking at it in the locker room!'' the older sister admonishes. It's almost time to hang up now. Venus is pulling into a parking space, on her way to meet one of her design clients. But Serena's in the middle of saying something, and Venus will surely have something to say back. So we sit for a moment, parked in the shade, as the two sisters trade chitchat from opposite sides of the country, blocking out the world beyond their connection.

Sara Corbett is a contributing writer for The New York Times Magazine.