This is the problem: They're too good.
It all looks effortless when they swagger onto the court. When they win, it's expected.
No hard lines etch their faces, like the ones we see with Jennifer Capriati, who came back from oblivion to be a contender. They are not as sensitive as Martina Hingis, who looks as if she could cry every time she drops a set. They don't grunt like Monica Seles hitting a backhand, or have the awkward feet of Lindsay Davenport.
Sometimes it seems as if they don't have anything better to do on a Sunday afternoon than go out and win a title in another Grand Slam tournament.
Other times it just seems wrong two sisters practicing together, walking out of the tunnel together, playing each other on center court, then going home together. Isn't there supposed to be at least a little venom in any competition?
That, perhaps, is the price to be paid for being one of the Williams sisters, Venus or Serena. They have become so dominant so fast that some have begun to question whether they're good for the game. Conspiracy theorists have even accused them of fixing their head-to-head matches.
This year's US Open is no different. All eyes are on them, as always. The public actually expects both to make the finals even though the women's field is strong at the moment. Venus is the defending champion, but Serena has won the last two Grand Slam events by beating Venus at the French Open and Wimbledon. If they do face off again in the Sept. 7 finals, expect more questions.
"There are a lot of experienced reporters out here who've covered lots of sports and what we see just leaves that air of 'was that real?' " commented one British journalist following the Wimbledon finals earlier this summer, in which Serena beat Venus in straight sets.
But if some observers consider their matches to be oddly lacking the usual competitive tensions, Stephen Tignor, managing editor of Tennis magazine, disagrees. "At Wimbledon they had all the characteristics of two people who were competing against each other," he says.
Regardless of where one stands, it is hard not to appreciate what the Williams sisters have brought to the women's game.
"They've done what Tiger Woods did for golf," says Tony Trabert, a winner of six major championships and a member of the Tennis Hall of Fame. "When they play, more people come out to watch. More people turn on the TV. More people go out and pick up a racket."
Tignor believes they could eventually be the two greatest players ever, even though Steffi Graf met with more success at a younger age by winning all four Grand Slam titles in 1988, when still a teen. "They've already upped the athleticism of the game," he says. "They're faster, stronger, and more powerful than any other women who play the game."
Both have games that are nearly complete. Venus, two years older than Serena, is a rangy player who can cover the entire court, play with touch, and outthink most opponents. Serena has more power especially on her serve and is extremely aggressive from all points on the court.
While Venus is the sister who has always received most of the fanfare, this summer Serena replaced her sister as the No. 1-ranked player in the world.
Richard Williams, their father and orchestrator of their careers, had always predicted that Serena would eventually be the better of the two. Right now is too early to tell, considering that they both have their best years in front of them.
When the Williamses joined the tour in the late '90s, they immediately stood out. Part of it had to do with their skin color they were black playing a mostly white sport.
Part had to do with their behavior, which, though not malicious, was far from the mainstream of the Women's Tennis Association. Early in their careers they appeared aloof, and when cornered, they became defensive. Much to the chagrin of others who lived for the circuit, the Williams sisters handled the tour like a part-time job, sometimes missing events for school and social events in Compton, Calif.
The declarations by their father that his girls would some day be the two best in the world did not help.
"People are jealous and there is still prejudice in the country toward African-Americans," says Richard Lustberg, a New York psychologist who works with athletes. "But the truth is that they are charming, lovely, and courteous young ladies."
Trabert agrees. "Now they handle themselves beautifully," he says of their maturation since Serena won the US Open in 1999 a surprise because her sister was clearly better at the time and Venus won Wimbledon in 2000.
They have also become role models in the African-American community, following the leads of Althea Gibson, a Wimbledon winner in 1957, and Zina Garrison, a Top-20 player in the '80s and '90s.
"It is my observation that young inner-city kids, when they see the Williams sisters playing at such a high level, become inspired to not only play tennis, but excel at other things," says Joseph James, chairman of the American Tennis Association, the country's oldest African-American tennis organization.
So when will people start judging them by just what they are, the two best female players in the world?
It might take a while. Every fan loves an underdog. And that is one thing the Williams sisters certainly are not.