With a hollow pop, my opponent's serve zips off the front wall, low to the back left. Rubber soles squeal against high-sheen wood as I lunge sideways and backward. The ball brushes the side wall at 80 mph, skims the corner, digs in its heels mid-air and drops to the floor, velocity zero. I'm poised for a bounce that will never be.

"Fifteen-four," my partner says sweetly. Mild-mannered at the keyboard, her persona on court is ruthless as promised.

Racquetball, trendy descendant of handball and squash, is carte blanche for nice girls to be cutthroat competitors.

"This is so much fun. I haven't beaten anyone in a while," she says.

Relax, I tell myself, you didn't expect to win the first game. Inch closer on the serve, stay in the center, keep your eyes on the front wall and concentrate.

"Susan won't play anymore because I nearly broke her arm with my racquet," my opponent says.

"I've heard." Not to worry. Doing some serious sweating now, muscles quaking, I'm working on the placement of the serves.

It turns out, on-court aggression is contagious.

See, anyone can play a vigorous game of racquetball the first time out. Tennis players are proficient after five minutes of adjusting to the 18 inch racquet, the high-speed 2 1/4 inch rubber ball and the confining court. (The 20 inch-by-40 inch floor, the four glass or wooden walls and the ceiling are legal playing surfaces. No net to jump over at the end of the match; nowhere to chase stray balls.)

But with practice comes sneaky finesse. My opponent, for instance, demonstrates a surprising range of vicious, hostile and nasty moves -- nice shots if I could duplicate them. Unreturnable serves that breeze by, three inches from the floor but miles out of reach; shots that hit the wall just where the wall hits the floor and dribble away laughing; calculated whammies that evaporate at angles you've never read about. Placement is the key. Hard hits, devious maneuvers and a lust for blood don't hurt, either.

So would a psychiatrist call racquetball an outlet for repressed hostility? "Why can't a game be a game without being a release of rage against this, that or the other?" asks Washington psychiatrist Norman Tamarkin. "Why bring psychiatry into everything?"

Colleagues who prepped me for this game said I'd be flung against walls, hit with balls, smashed with racquet and body and freaked out by the boundless drive of my opponent. Like so many young professionals who schedule games around office hours, she leaves passivity in the locker room. Where 10 years ago women said "Oh! Sorry," if they nudged a player en route to a backhand return, now they're jockeying for the limited space at center-court, with assertiveness-trained elbows.

"Women are just as competitive and aggressive on the court as men and can be just as obnoxious," says Phil Kaplan, the racquetball pro at Skyline Racquet & Health Club in Falls Church. "They get angry, cuss and slam their racquets the same way."

According to projections by the U.S. Racquetball Association, by the end of the year 40 percent of the country's 14 million players will be women. (In 1970, only five percent of the 50,000 players in the nation were female.)

Heart-pumping, I take a giant, well-meaning swing, hoping to ricochet the ball from the back wall to the front. Somehow it doesn't connect. My inner monologue is increasingly vile as I struggle to stay cool. I jump up and down like a Wide World of Sports star, awaiting the next monster serve.

Of course, the it's-not-who-wins-that-counts mentality persists among some old-fashioned players, who haven't heard that trouncing the opponent is a different sort of high. Phyllis Komack, captain of the ladies B-team at Courts Royal in Rockville, denies bringing animal aggression to the sport. "It's a tension release, but I play for the fun of it," she says. "It's not worth getting hit in the face with a racquet. My teeth are more important to me than winning the point."

I'm telling myself something about holding my head up back at the office but I'm panting too hard to hear. It's Game Three on court seven at the Rhode Island Avenue Y and I'm taking a beating. A modest jock, accustomed to sweating for exercise, and not over the score, I gave in to friends and invested $10.50 in Foster Grant safety glasses. I'm not ungrateful now, the black elastic band snug around my head and bullet-balls whizzing past my eyebrows.

15-4, 15-5, 15-6. "Maybe next time you'll get seven points," my opponent says.

Next time? I nod my warmest regards, fuming, and dam two streams of sweat running past my jaw. I stretch my tense back, blot my sticky palms, and, dancing Bjorn Borg-stlye in the server's box, begin again.

But now I've figured out her "Z-ball," the one that doesn't bounce where you think it will but parallels the wall, inventing its own geometry, the better to skip you around the court. I'm on to her.

In fact, for three seconds, it's 4-0, my favor. A round of huffing grand slams and smart-alecky teasers ensues. A silent stream of verbal abuse. Why aren't the next scheduled jocks banging on the door to throw us off the court?

Thankfully, it's over: I've cut my losses, 15-12.

My hands are trembling, blood is pumping wildly. "Wanna play again sometime?" she inquires.

I pause, think of the three lousy shots I could have aced and know I'm hooked. NEXT TIME I WILL KILL FOR 15 POINTS.