NEW YORK — Chris Evert had hardly enjoyed her place as the apple pie of American tennis in the mid-1970s before Tracy Austin, the next pigtailed, double-fisted phenom, encroached. Another, Andrea Jaeger, wasn't far behind.
In a sport where a single star can inspire copycat generations — consider the wave of Swedes that followed Bjorn Borg — Evert was puzzled. Where were the Venus and Serena Williams clones?
This was not one, but two great, boundary-redefining champions from the same family.
"I wondered five years ago," Evert says. "They had been in the game for years. Why weren't there more African-American players?"
From top-seeded Serena's opening-round opponent, 18-year-old Taylor Townsend (Tuesday night, Arthur Ashe Stadium), to top-30 players such as Sloane Stephens and Madison Keys, the female contingent competing at this week's U.S. Open is teeming with diversity.
Nine of the top 14 ranked American women are African-American, Asian, Latina or mixed race, including five of the top six: Serena, Venus, Stephens, Keys and Christina McHale.
"Who knows if they would have played if Venus and I didn't?" two-time defending U.S. Open champion Serena said in a recent interview. "But we feel like we had something to do with it."
There is little doubt the landscape of American tennis, especially on the women's professional level, has never been more diverse, even if direct correlations to a "Williams effect" are difficult to validate.
"It's hard to say," says Katrina Adams, the first vice president of the United States Tennis Association (USTA) board and also executive director of the Harlem Junior Tennis and Education Program. "I'm sure they sparked an interest in a lot of little girls in particular to play the sport."
Demographics on a grass-roots level have been shifting as well.
According to a 2012 Tennis Industry Association survey, participation among African-Americans hit a 10-year high from figures compiled back to 1988. Hispanic participation was the third highest during the last decade.
Other anecdotal evidence abounds.
Rodney Harmon, a former ATP pro, worked nearly 18 years as a coach at the USTA, most recently as director of men's tennis.
Now the head women's coach at Georgia Tech, Harmon has three highly sought-after African-Americans on his team. Plus, he's noticed much more diversity on his recruiting trips.
"I just came from the 18s and 16s nationals in San Diego and saw a lot of minorities, much more than when I was coming up," said Harmon, who is black.
There has been less obvious impact in the men's pro game.
Only two of the top 10 American men are of color: Donald Young and Rajeev Ram, who is a second-generation American of Indian descent.
However, two of USA's top prospects are black: 16-year-olds Francis Tiafoe and Michael Mmoh.
Observers say that is a product of more opportunities and better marketing aimed at young boys in sports such as basketball, football and soccer.
But it's also because there has been nothing close to the iconic status of the Williams sisters in American tennis since Arthur Ashe and Althea Gibson despite a history of success among non-whites, from Zina Garrison and Chanda Rubin to MaliVai Washington and James Blake.
But, does diversity even matter?
Garrison, a 1990 Wimbledon finalist who emerged from public programs in Houston, said it does, particularly when it comes to attracting a wide breadth of talent into the sport.
"First interest in my opinion is someone that looks like you," said Garrison, who is black and now coaches Townsend.
She added: "You can't send someone into the 'hood and get them to identify. It doesn't work that way. You need those great player icons like Venus and Serena, and people that are there already that are teaching in the trenches. You need all of that."
The non-profit USTA, the governing body of tennis in this country, has been making solid inroads with minorities in a variety of areas, according to D.A. Abrams, the USTA's chief diversity and inclusion officer.
This includes community outreach, suppliers, training and development and via tennis leagues, school and park programs, and grants.
"The tennis industry will only survive if you have more people playing tennis, and more people playing frequently, from a business and popularity standpoint," Abrams says.
But nothing inspires like star power.
"(The Williams sisters) made tennis cool for anybody and everybody," Garrison says.
Among many of today's pro players, the Williams imprint is undeniable.
Illinois-born Keys, 19, took up the game at age 4 when she saw Venus on television — and liked her dress.
Townsend, a bubbly left-hander from Chicago and a former junior No. 1, grew up playing with her older sister, who blew out her knee at 15. The comparisons came hard and fast. They ate them up.
"She used to kick my butt, which is kind of the same when Venus used to beat Serena," Townsend says of her sister. "They were influential to me because they were trailblazers. We were like, 'We can do it. Look at what they are doing. We could do the same thing.' "
Southern California's Stephens, 21, idolized Belgium's Kim Clijsters growing up.
But she, too, said it was impossible to avoid the Williams sisters' reach, even if her relationship with Serena seemed to sour last year based on comments she made to a magazine calling out the No. 1 for being phony.
"The Williams sisters influence everyone," said Stephens, who first became aware of the sisters when she saw Venus on TV in the 2005 Wimbledon final against Lindsay Davenport. "They are two of the greatest players to ever play the game of tennis. So obviously, of course."
Many say the impact of Venus 34, and Serena, 32 could last for years.
There have starkly different personalities that appeal to a wide variety of people. Their back story and rise from the streets of Compton, Calif., is compelling. By dabbling in acting and design — they also are no strangers to red carpets and late-night shows — the sisters have forged global crossover appear.
And of course, there is the pack behind them — and at this point not too far — eager to grab the baton from the seemingly ageless stars, who won't be around forever.
There are those that say the USTA still isn't doing enough to bring the game to minority populations, among them Garrison, a former Fed Cup captain who in 2009 settled a racial discrimination lawsuit against the USTA.
"We've come a long way from being a country club sport," she says.
She believes a wave is gathering.
"We have a new group that will be impactful in their own way," she says.
Evert, an 18-time Grand Slam champion, expects to see more champions of color ahead.
"It's remarkable," she says of the changing face of American tennis. "And about time."