If tennis has lately taken on the fleeting quality of a video game, it's because a 14-year-old, Jennifer Capriati, is conservatively worth $5 million; a 16-year-old, Monica Seles, challenges for the No. 1 ranking; and a 21-year-old, Steffi Graf, is made to feel old. These phenomenons are merely the latest instances in the ongoing debate of whether children are meant for everyday use in tennis. They also may be evidence that money and supercharged equipment have changed the game irrevocably.

In the era of the prodigy, youths support their parents, adolescents sprint to the top of the world and tumble back down, teenagers are sophisticated travelers to Paris yet have never been inside the Louvre. Aesthetically, they are moppets playing a power game with wide-body rackets that emphasize force over feel. They are better and younger all the time, but there is a growing consensus that their fast-forward careers may be shorter.

"I don't see myself playing at 27, 28," Graf said recently. "At least I don't think so. It's what I already have a little bit in my mind."

When the U.S. Open begins Monday at the National Tennis Center on the edge of New York City, 37-year-old Jimmy Connors, finally tired out after 20 straight appearances, will not be in the field for the first time since 1970. Meanwhile, 18-year-old Michael Chang continues what he termed a "comeback" after fracturing his hip in December. Martina Navratilova, 33, still pursues the women's No. 1 ranking held by Graf, who won the Grand Slam at age 18 but is already harried by pressures and the two-fisted fledgling Seles. The reigning French Open champion is No. 3 and could be No. 1 by the end of the year with an Open title.

Just who this new set is and what they represent still is being determined. "They don't talk," said one high-ranked veteran. Andre Agassi, the 20-year-old who has yet to break through with a major victory, nevertheless has a multimillion-dollar clothing and shoe contract with Nike. His advertisements may be the best expression of the turn the game has taken, ear-splitting, staccato drums and a dizzying series of picture bites, flashes of hot lava acrylic.

"I feel like all I'm getting are glimpses," Billie Jean King said.

Navratilova doubts that any of the new crop will play into their 30s. She grew up playing tennis for only a few hours a week until she was 14 and began training seriously. "I think that's why I'm still around, quite frankly," she said. Graf turned professional at 13. In trying to explain her short-term view, she said she doesn't think she has Navratilova's stamina, faced with ambitious younger competition and spiraling pressures she says Navratilova's generation did not have to face.

"I started at 13, 14 years old playing the tournaments all around, all year round," Graf said. "At her time there wasn't the competition there is now. There wasn't the pressure from the outside, the involvement of the sponsors, the press, everything around it. So I think that she still has some reserves that we, the younger players, won't have at 30, that's for sure."

The inherent dangers in children turning professional and playing full schedules in any sport are, by now, well known: physical stress, mental burnout and distorted values. Tracy Austin, a 16-year-old U.S. Open champion in 1979 and No. 1 in 1980, was by 1983 a victim of persistent back injuries. Andrea Jaeger turned pro in 1980 at 14, was a Wimbledon finalist in 1983 and ranked as high as No. 2. But by 1984 she was not only virtually inactive with arm and shoulder ailments, but ambivalently wavering between tennis and a college education.

The same problems are present on the men's tour if to a slightly lesser degree, as players mature later. Chang, the youngest winner of the French at 17 last year, fractured his hip in December and is starting over, a respite from high expectations it turns out he may have needed. "I think it helped me a little bit," he said. "I can relax and just go out and play without having to worry about being labeled the French Open champion."

Those syndromes do not have to be the norm: There is a wealth of new methods and ideas to combat them, from improved physical therapy to sports psychology, to rules limiting the number of tournaments younger players can enter. And by all accounts the group so dramatically represented by Seles and Capriati is better equipped, informed and adjusted to life on the circuit than former prodigies. "They're different," King said. "They've got it."

Also in the clique are 18-year-old, No. 6-ranked Arantxa Sanchez Vicario of Spain, the '89 women's French champion; 19-year-old Australian Open finalist Mary Joe Fernandez of Miami, and 19-year-old Pete Sampras, who has risen from No. 56 to No. 12 this season. Among the traits they share are uncommonly well-developed physiques for their ages. Capriati is already 5 feet 6 and 130 pounds. They also share composure, and a healthy sense of enjoyment.

"I'd like to be free of injuries, no problems, and just enjoy tennis," Seles said. "If I start not liking tennis or thinking about a lot of other things, then I think tennis will become difficult. For me right now it's fun, and when it's not fun I think I will stop. Whether it's two years or tomorrow, as long as I like it, as long as I enjoy, I will be on the court."

But none of the new methods is as effective as common sense, a quality that often seems lacking. No matter how talented they are, there is something faintly disturbing about a group that carries schoolbooks to tournaments, particularly when the players in their 20s such as Graf and Gabriela Sabatini of Argentina, who has slipped from No. 3 to No. 5 this season, are struggling with the ramifications of starting so young.

"I have to say it's really strange at 21 to have to play so much younger girls," Graf mused after beating Capriati in the fourth round at Wimbledon. "I mean, I don't feel old. You realize that it's just weird."Money, Money, Money

There is nothing like several million dollars to override common sense. Even before Capriati made her professional debut this spring at age 13 she signed widely publicized, million-dollar contracts with the Prince racket firm and the Italian clothing and shoe company Diadora. Her newest endorsement is with Oil of Olay, the skin cream that keeps you youthful. She has risen to No. 13 with a record of 32-8, including a semifinal appearance in the French Open. Seles has her own clothing line and just signed a new racket deal with Yonex, and her total earnings may exceed $4 million.

Capriati and Seles profess to be ignorant of their worth. The bottom line on the money issue may be this: The great ones don't play for it. They play to win. "I mean, if I didn't feel that way, why should I even try for it, you know?" Capriati said. "I mean, that's the way I go into every tournament." Seles has a voracious seven victories in the 11 tournaments she has entered. At the beginning of last year she was not in the top 100, this year she has risen from No. 6 to No. 3.

"I never even look at it really," Seles said. "For me it's really just the tennis. More important, I would say, than anything else, is if I would know that in 10 years I can play perfect tennis."

Yet their earning power separates today's players from yesterday's more than any other single development in the sport. And according to King, it may be a significant factor in abbreviating careers. "Let's face it, it's the money," she said. "They have choices even a lot of recent players didn't." In short, players no longer have to play to ensure their immediate livelihoods or long-term security, something even Navratilova still is trying to do.

"Capriati's 14 and she's got her own shoe with her name on it," Navratilova said. "In 1974 I signed a deal with Etonic for $1,000 a year and I thought I was hot stuff."

Agassi has worked desperately to improve his strength and defends his somewhat underachieving record by saying he is developing at his own pace. Certainly he can take his time, with $3.5 million annually, including his own shoe, the Air Tech Challenge. But Connors wonders if money doesn't have its subtle effects. "I don't see a lot of guys who have it in them to grind it out day to day," he told the Associated Press. "I don't know, maybe it's too easy."

With money has come the entourage, which for any given player can include parents, agent, coach, trainer, dietitian, shoe representative and bodyguard, a protective and potentially blinding ring. "Maybe I started it," Navratilova said wryly. "But at 14 I think you can go a little overboard." While money and the accompanying buffers can relieve pressure, they can also create it, leading to the "pushing" of a young player. The more significant the money and the larger the entourage, the more difficult it may be for players to make themselves heard. "You have to be able to say no," Navratilova said.

But Seles is at least one player who sees the furor as exaggerated. She lacks a noticeable entourage and appears to be a model of self-determination.

"A person should have individuality on and off the court," she said. "It's hard because maybe you are pressured into some things by some people, but when you really think about it, it's totally your decision. Nobody has a say in it."The Push to Succeed

That Capriati and Seles would capture the imaginations of little girls everywhere, and that their contracts would capture the imaginations of ambitious parents, was probably inevitable.

Before she became a pro, Capriati's coach, manager and father, Stefano, had her extensively tested at the Virginia SportsMedicine Institute in Arlington in an attempt to detect weak or trouble spots in her physique. According to Janet Sobel, the institute's director of rehabilitation, since Capriati's debut there has been a mad rush of parents and children to the testing facility.

"You can't believe the number of parents with their 9-year-old kids," Sobel said. "And the only question they asked is, 'How did she compare to Jennifer?' It's depressing. A lot of these kids are being pushed. It's happening."

Capriati's tests were performed in 1989 when she was 12. She scored extremely well in aerobic capacity and body fat percentage (12.8 percent), and did 42 situps in one minute. But there was worrisome news also, with noticeable weakness in her external rotators and muscles surrounding the shoulders. She also showed some inflexibility in her hips, hamstrings and lower back, all common areas of weakness in young players. She was given a comprehensive set of exercises and stretching routines, which Pam Shriver could have used a decade ago.

Shriver was labeled a comer when she made the final of the U.S. Open in 1978 at 15. Two years later she had recurring arm and shoulder problems, which have persisted. She skipped Wimbledon and will miss the U.S. Open, recovering from arthroscopic surgery. "By 16 or 17 I had the arm problem," she said. "The upper body strength in females gets real dicey. If I could do one thing differently it would be to get a heck of a lot stronger."

None of that is to say the current crop of players isn't physically and mentally qualified to play the circuit, or that it is inherently wrong for them to be there. Chris Evert is the standard, debuting in the U.S. Open at 16 and retiring there last season after 18 years, a relentless example of how to handle pressure and avoid injury with her precise, flawless mechanics. What Sobel warns is that each case varies.

"Sometimes you get an extremely fit, healthy athlete like Jennifer," Sobel said. "But she's unusual, a very unusual kid both physically and psychologically. There's been a huge assault on her, but she's doing great, she's very balanced."

According to Shriver, there is an easy way to tell if a junior should be permitted to play the circuit: the rankings. She maintained that if they don't show an ability to play among the top 50 consistently, they should be in school. "To me it's horrendous if you're anywhere from 14 to 19 and you're on the tour and you're not in the top half of the hundred."

Above all, there is the danger that they play too much. Seles lost in the early rounds of her first three tournaments this year, suffering from a growing spurt and chronic stiff shoulder. In addition to the physical costs, there are the less tangible social ones. Capriati complained of homesickness and missing her dog during her 10-week stint in Europe, only to return to a loaded schedule. She is moving from her home and school in Saddlebrook, Fla., to a club in Boca Raton, where an endorsement deal has been negotiated for her.

"The day after the Open finished in 1978 I was back in school," Shriver recalled. "I was a U.S. Open finalist, and a senior at a prep school. That was tough. It was a little weird. You definitely don't fit in with the rest of the group."

King contends that injuries, particularly small, nagging ones, can be signs of more than just physical vulnerabilities. They can indicate mounting unhappiness and worries, particularly if parents have quit jobs or made significant sacrifices to train offspring, who are all too aware of what is riding on their successes and failures. She equates the tennis prodigy with the overachiever in school, who becomes too upset when he or she doesn't get straight A's.

"I think a lot of times what they're saying is, 'I'm overwhelmed,' " King said.

Seles, Capriati, Chang, Agassi and their peers are not overwhelmed. They are overwhelming. They also are blessed with apparently cheerful, durable dispositions. "That may be a saving grace," said Mike Estep, coach of Sanchez Vicario. But coaches and parents alike are constantly mulling the fine line between letting gifted athletes pursue their ambition, and yet maintaining a reasonable lifestyle and broadening their experiences.

"As a coach I wouldn't have any moralistic judgment," Estep said. "But as a parent I think I'd feel some concern for the loss of those teenage years. It will be a long time before we can judge the results. There are the Jaegers, and then there are the Everts, so I don't know. After the applause is gone and the career is finished, to be able to understand Eastern Europe or the stock market is valuable. To not be able to understand, you might be wasting a life."

But there is a common refrain among the great young players that tennis is not costing them anything. For some, it may be an indispensable passion; Evert once called it "a need." Capriati steadfastly maintains she isn't missing a thing because she loves the sport so completely. Chang perhaps most eloquently summed up the curious enjoyment younger players are finding in both playing a game and building very adult careers in a high-pressure, disciplined arena.

"I always take tennis seriously," he said. "When I play tennis, that, to me, is a pleasure. That's why I make it my career. To me, I don't feel like it's wrong to have an obsession to win something. The pleasure, I think, is in playing great points and being in the very tense situations, the great serve, the great volleys, the great returns, the great shots."