BARCELONA ’92 OLYMPICS / DAY 12 : In Own World at 16, Capriati Quiets Nation : Tennis: Unaffected by presence of the King and Queen of Spain and a loud crowd supporting her opponent, she beats Sanchez Vicario, 6-3, 3-6, 6-1.

For once, being 16 years old served Jennifer Capriati quite well.

When she slugged her way into the women’s singles gold-medal match at the Olympics on Wednesday, she did so against a backdrop of staged ceremony and nationalistic fervor that might have unnerved even the most seasoned tennis veteran.

Capriati, however, wasn’t the least bit shaken because she didn’t know she was supposed to be.

The scene:

--A packed center court at the Olympic Tennis Stadium, a sprinkling of Spanish and Catalonian flags in the stands and the darling of Barcelona tennis fans, Arantxa Sanchez Vicario, her opponent in the semifinals.

--Whenever things went badly for Sanchez Vicario, a cadence chant swept the stadium: “A-ran-cha (clap, clap-clap)” . . . A-ran-cha (clap, clap-clap).”

--Sanchez Vicario, buzzing around her favorite slow clay surface like a mosquito, playing to the hugely partisan crowd with withering looks at linesmen on close calls and clenched fists toward the stands on crucial shots.

And then it really got crazy.

Capriati, playing marvelous tennis, jumped to a 4-0 lead in the first set and, while Sanchez Vicario started to find her range, Capriati finished out the set, 6-3.

Then, with the Spaniard trying to get something going at 2-3 of the second set--and with Capriati poised to serve--umpire Bruno Rebueh of France asked for a delay in play as a large group of people filed into the VIP seats on the far end of the stadium. Soon, the photographers were snapping and the spectators were craning their necks, as the whisper circled the stadium: The king and queen had arrived.

Indeed, as Capriati, a high school sophomore from Saddlebrook, Fla., wrinkled her brow and fidgeted over the delay, King Carlos and Queen Sophia marched in, accompanied by their two daughters and one son, and sat down in the plush, red-velvet, high-backed seats that had been empty for most of the tournament. Queen Sophia nodded in the direction of Sanchez Vicario, only a few feet in front of her down on the court, and play resumed.

The mosquito became a hawk. She ran down everything, got to break point on a let cord and broke for 4-2 when Capriati hit a backhand wide.

Quickly, the set was over, with Sanchez Vicario closing at the net on set point for a crisp forehand volley and clenching her fist triumphantly in the direction of the king and queen.

For most, the scene would have been too much to handle. The outcome of the third set seemed inevitable. Kings and queens don’t come to see defeats.

But defeat they saw, as the American teen-ager, obviously with a better feel for backhands and forehands than ceremony and royalty, crushed Sanchez Vicario in the third set to close out a 6-3, 3-6, 6-1 victory. That put her in Friday’s final against Steffi Graf of Germany, who ran past American Mary Joe Fernandez, 6-4, 6-2.

When Capriati met reporters afterward, the obvious question was how she had managed to overcome all that was going on around her. The specific question was: “What did you think when the king and queen made their entrance?”

And her reply explained it all. She didn’t think anything at all, she said. She didn’t know who those people were. For Capriati, the King and Queen of Spain hold considerably less appeal than, say, Prince from rock ‘n’ roll.

“I just thought it was a bunch of people coming in late during a changeover,” she said.

Capriati didn’t even know that she didn’t know. And in her case, ignorance was truly bliss.

And to be fair, there probably shouldn’t have been expectations that she should respond to an adult situation as an adult, which she is not. She met reporters wearing a loud green and red T-shirt, a black baseball cap with the bill tipped up, her bangs combed straight down into her eyes and her longish fingernails painted red. And in answer to one question about life in the athletes’ village, she replied, “It’s real fun.”

Within the teen-ager’s body, however, are adult tennis skills. Her steady play on the clay here has prompted many to predict an upset of the top-seeded Graf in the final.

“I think I have a good chance,” Capriati said. “I’ve just got to play my game, be aggressive and serve well.”

She also must face the new Olympic record-holder for most singles victories. Graf’s victory over Fernandez, who has never beaten her, was her 10th since the sport returned to full medal status at Seoul in 1988.

“Truth is, I haven’t looked at my Olympic medal all that much since I won in Seoul,” Graf said. “It’s in a room I have where I keep my trophies. But I will admit, before I left for here, I went in and took a little peek at it.”

The bronze medal that Fernandez won for gaining her semifinal berth, and the silver or gold that Capriati will win Friday will be in addition to whatever Fernandez and her doubles partner, Gigi Fernandez, win. They are in the women’s semifinals, assuring them of a bronze, and will play for a berth in the final today. No U.S. men’s player won a medal.