Messed up little boys and girls are not at all uncommon in the grass-green and asphalt-black world of suburbia. They romp cheerily among the trees and mopeds, chattering about Betamaxes and analysts. Often it's so hard to distinguish one from another amid the swirl of LaCoste and Adidas, that concerned parents just scoop up a convenient horde at sunset, hoping to extract their own offspring by dinner time.

But you can always pick out the little boys and girls who play in junior tennis tournaments, the rascals with the headbands scrunched down over furrowed little brows. Sullen looks, knee braces and mumbles about "bum draws." These kids accept intense jealousy, incessant selfdoubt and occasional deceit as the basis of achievement right along with hard work and lots of orange juice. I know, because I was one once.

I would like to say that at the age of 15 I realized that shoddy cartilage would prevent me from keeping pace with my dear buddies on the tour. In fact, I discovered that my frantic desire not to fail outweighed all the practice swings and wind sprints. I choked more often than my peers and rarely rose to the occasion when facing a superior. Finding little solace in the chilly locker rooms of indoor racquet clubs, I returned to the easy glory of high school competition and old men's doubles.

What I am left with is good form, a potentially dangerous, but woefully inconsistent, game and the ability to say, "I once played next to John McEnroe at Port Washington, and he got so mad that he threw his Prostaff over the nylon netting and onto my court." (True story.) I also saw Jimmy Arias, the United States' next great player, knock forehand winners when he couldn't have been more than three feet tall.

I saw Arias again last week, losing to Jaime Fillol in the first round of the Washington Star International Championship in Washington D.C. The 15-year-old is a lot taller now, but his arms are still thin, his torso unmuscled. Arias lost the tight three-setter to the crafty Chilean because he was unable to maintain the brilliant level of play that repeatedly brought the crowd to its feet and a puzzled frown to Fillol's face.

The youngster lacks the umph that 30 more pounds would give his groundstrokes. He compensates by overswinging under pressure. Carefully tuned topspin dissolves into desperate flailing when he is faced with consistent, deep, professional offensive strokes. But given any opening, the kid attacks fearlessly, uttering pubescent versions of the Jimmy Connors "I'm kicking butt, Mom, really I am" grunt. His serve is already an explosive weapon. His mobility--though not exceptional--is adequate.

"So what?" says you. "We knew since the time he began snagging national championships at 10 that Arias was a winner. Why rave now?"

Well, when Jimmy Arias was nine and 10 we knew he was good, the class of his crop of little monsters, but he was still just that, a little monster. One tyke who had the misfortune to face Arias several times in those early days told me over a tennis camp lunch once, "He's great. He's the best. He's also an asshole, and I bet he gets screwed up."

Jimmy Arias isn't an asshole any more. He doesn't toss his racquet or curse; he pouts only occasionally. More often he follows a miscue with a fierce sneer as he stomps cross court, determined to punish the ball for betraying him. The youngest player ever to receive an Association of Tennis Professions (ATP) world ranking has risen above the junior tennis mentality that constricted my back hand on big break points and has been the downfall of many wunderkind who far surpassed me in talent. He is playing now to challenge himself, to fulfill a greatness he knows is his, not to prove that thousands of dollars of lessons have paid off.

Jaime Fillo is 34 years old, is president of the ATP and has faced the game's most fearsome giants. He didn't just praise Arias's grace or poise in a post-match interview. Fillo said flat out, "I think Jimmy already is playing better than Connors at that age." Jaime Fillol knows he could very easily have lost that match.

. . .

The bottom end of the junior tennis circuit is not a very nice place to spend your childhood. Who wants to hang around with lots of kids from California and Long Island who regularly whup you in front of Mom and Dad? The experience did, however, teach me a lot about who I often perform for and why it hurts so much to lose. And I got to see Jimmy Arias playing like the little brat he once was. You will probably see him heave his racquet someday too--but only in joy, after hitting a scorching passing shot for game, set and match.