Being a teenager isn't what it used to be, at least if you're a female tennis player.
The women's game has had a long tradition of success at a young age, from 15-year-old Charlotte "Lottie" Dodd's Wimbledon victory in 1887 to 16-year-old Martina Hingis' Australian Open win in 1997.
But the prodigies that once populated the women's tour are now few and far between.
Caroline Wozniacki carried the teenage banner for a while this year, reaching as high as No. 2 in the world as a 19-year-old. But she had turned 20 by the time she ascended to No. 1 last month, leaving Anastasia Pavlyuchenkova as the only teenager in the top 40. In the top 100, there are six teens, compared to 10 players who are 30 years or older.
Where are today's Tracy Austins, Jennifer Capriatis and Martina Hingises?
"Physically, I don't think I could break into the game today at the age of 14," Austin says. "I weighed 89 pounds back then and the women are so much taller and stronger now."
Well-known coach Darren Cahill, who works with several WTA players as part of the adidas player development program, concurs that the barrier is primarily physical. "They were incredibly successful at a young age because they hit the ball as hard as the best in the world," he says. "The young kids coming through today don't. It's as simple as that.
"The ladies' game in the last 5-10 years has become much more of a power game. You've got to develop more physical strength, and that only comes with years of training, putting in the off-court training and building that body.
"And it's tough to do that when you're a youngster."
The trend toward bigger, stronger players has been amplified by more forgiving rackets and the new synthetic strings, both of which allow power to take some of the place of technique.
"I think technology has played a small part," Cahill says. "The players these days, with the technology in the string, are getting a little more spin on the ball, which means they can string their rackets a bit looser, and they can hit the ball harder."
The WTA Tour's age-eligibility rules have also played a role in slowing down the pace of development, barring players younger than 15 from playing at tour level and limiting them to a part-time schedule until 18.
"Its intentions are all good, but by the time that most girls reach 16 or 17, they already have physically matured and they need to have enough WTA Tour-level matches in order to progress," Austin says. "No one should be pushed into overplaying, but you can't have promising players being forced to sit for a month or two and expect them to get the experience they need, and the results that they want."
It mirrors a similar trend on the men's side. Boris Becker and Michael Chang both won majors as 17-year-olds in the 1980s, but there are currently no teenagers in the top 100.
This season's breakout WTA players have largely been mid-career veterans, such as 26-year-olds Samantha Stosur and Vera Zvonareva and even 30-year-old French Open champ Francesca Schiavone, who always possessed ball-striking talent but have now learned to harness their skills during important occasions.
"Early in my career, I would get a bit nervous and not be able to close [matches]," Stosur says. "But I've matured, and you only get better by being in that situation."
Yet it was once prodigious teenagers such as Austin, Chris Evert and Monica Seles who were known for their mental toughness. "I wasn't intimidated by any of the elite players I faced, even though it took me a while to get used to Martina [Navratilova's] overwhelming power," Austin says. "Once you have a champion's mentality, you'll always have it."
But today's teens have proven more prone to choking or imploding at key moments, which may be a manifestation of the gap in power and strength. "I think one's related to the other," Cahill says. "They know they've got to work much harder, they've got to get much stronger -- there's probably a level of frustration that creeps in because of that."
So is the era of wonder kids over? Mark Wellington, a trainer who has worked with Victoria Azarenka and Maria Sharapova in the past, feels that teens can still have isolated success like Sharapova's Wimbledon victory at 17 in 2004. But like Rafael Nadal on the men's side, a teenager on the women's tour would have to be unusually physically precocious to become a regular Grand Slam threat that early.
For many players, matching and dealing with the current level of power hitting is all they can handle -- no room to indulge in luxuries like variety and touch. But with everyone smacking the ball, it's those who can do a little more that are distinguishing themselves.
"Ten years ago, if you were a female player and you could hit it harder than your opponent you would win," Wellington says. "Now the top 10 is full of big, strong players who also know how to play. It is the whole package.
"To develop those physical skills, the biomechanics of movement, the biomechanics of hitting the ball, [and] gaining the experience of playing at that level is very difficult at a junior level now."
A few young players have managed to climb into the top 10 recently -- Wozniacki, Azarenka and Agnieszka Radwanska. But, as Wellington points out, both Wozniacki and Radwanska built their early success on tactical savvy and lithe movement rather than power hitting. Trying to take the next step, Wozniacki has had to work on getting stronger and playing more aggressively.
Even Pavlyuchenkova, the most accomplished of the current generation of teens, is still filling in pieces of the puzzle. "I'm working on a lot of things, and I have to bring it all together," she says. "Sometimes I'm working on my serve and my legs don't move, for example.
"Sometimes I play unbelievable and sometimes nothing special."
A Lasting Generation
The increasingly multifaceted demands at the top also help explain why the best players of the past decade have had such staying power. More than half the players who ended the 2004 or '05 seasons in the top 15 were also in the top 15 at some point this year -- Serena Williams, Venus Williams, Kim Clijsters, Justine Henin, Sharapova, Svetlana Kuznetsova, Zvonareva and Schiavone.
Henin, who ended an 18-month retirement at the beginning of the year, observed that her competition remained largely the same as before she had left: "Kim, Serena, Venus, still; Kuznetsova, Dementieva [now retired] after that."
They came along in the early 2000s, the first wave of players who were tall and powerful but could also move well. It was an evolutionary leap, one that has allowed them to maintain an edge over the new hopefuls who are trying to catch up.
"I don't think we'll ever see women's tennis become more powerful and more physical than it has been over this last decade," Clijsters says.
Though injuries, retirements and limited schedules have left room for others to make an impact in the rankings, this core group has continued to dominate the majors.
Serena has been the strongest driving force, breaking new ground for the women physically and continuing to improve her game and raise the bar. "She's put herself that much far ahead of the field." Cahill says. "The field had to become better tennis players."
For Serena, then, the aging of the tour is pretty self-explanatory: "I think pretty much everyone got older and aged. I was a teenager once."
Kamakshi Tandon is a freelance tennis writer for ESPN.com.