SAN JOSE, Aug. 16 -- The same girl who broke into a cold sweat when she saw herself on television for the first time six months ago entered HP Pavilion on Thursday night as the focal point of United States gymnastics. Shawn Johnson, 15, posed for pictures and signed autographs as 5,000 fans watched her on the JumboTron. When she was introduced over the loudspeaker, Johnson responded with a shy smile and awkward half-wave that illustrated a sentiment she had already repeated several times here this week.

"It's all so new and weird," Johnson said earlier. "I guess I'm still not sure what it's like to be famous."

In about 10 months, Johnson has transformed from a talented junior gymnast into a candidate to win multiple medals at the 2008 Olympics. She has won every meet she's entered since joining the senior national team, including three gold medals this summer at the Pan American Games in Brazil. Johnson's peers expect her to win a few more golds this week at the USA Gymnastics national championships, which conclude with Saturday night's finals.

She took an almost flawless first step toward fulfilling those expectations Thursday, nailing all four of her routines to finish the preliminary round in first place. The public school student from Des Moines will enter Saturday's finals with almost a two-point lead -- significant enough that little less than a fall could keep her from winning. It will be a good test run, coaches said, for the circumstances that will define Johnson's next year: Only the burdens of pressure and notoriety can derail her.

"Sometimes I feel more pressure now, just because people have seen what I'm capable of, and I try to show them that every time," Johnson said. "But I still try to think about it like it's no big deal. I'm still, you know, young and just getting used to this. There's no way I can consider myself a star."

Johnson won the junior all-around gold medal at the 2006 national championships, and she has since made perhaps the most effortless transition into the senior division of any gymnast this decade. She is compact and muscular at 4 feet 10 inches, with long blond hair that she ties back with pink and white ribbons. Though she favors the balance beam, she could also contend for gold medals this week on the uneven bars, vault and floor exercise.

Coaches consider Johnson the preeminent athlete in a group of young gymnasts that could lead the United States in Beijing. As veterans Nastia Liukin, Jana Bieger and Chellsie Memmel age into their primes, USA Gymnastics has marketed Johnson as its next megastar. Her routines are crisp, graceful and thrilling to watch. For Thursday night, she had planned a remarkably difficult routine on the balance beam and a dismount from the uneven bars that required a double-twisting back flip.

"She's as complete a gymnast as anybody out there," said Liang Chow, Johnson's coach. "We spend a lot of time working on basics. Every day, we spend 90 percent of the time going over the same basics, so she is absolutely sure about everything."

Johnson has grasped for bastions of normalcy during her rise to prominence, but those escapes have become increasingly difficult to find. Her friends and teachers pester her about making the Olympic team. On Friday nights, she goes to high school football games to disappear into the student section, only to have school administrators pull her onto the field at halftime for congratulatory ceremonies.

Even though Johnson signed with an agent and turned professional this year, she remains adamant about graduating from public school -- no matter how difficult that's become. Meets and other gymnastics-related travel forced her to miss 50 days of class as a freshman last year. She squeezed seven hours of daily gymnastics practice around each school day, waking up long before dawn and sometimes staying at the gym until 10 p.m. to finish workouts. Friends suggested switching to a private school, or home-schooling, or taking a year off from academics.

"But I'm like: 'No way! High school is my only social life,' " Johnson said. "I don't care what else is going on. I can't give that up."

In May, Johnson and her parents -- an accounting clerk and a carpenter -- met with school counselors and customized a class schedule for the upcoming school year. Johnson will spend 90 minutes in the morning at the gym before starting school at 8. She will take five classes instead of the usual eight, skipping gym and a few other electives. Then she will devour a packed lunch and leave school at 1 p.m. for the gym, where she'll stay until at least 7.

Assuming Johnson performs up to her standards this week, that academic plan won't actually launch until late September. If Johnson qualifies for the world championships, she'll fly directly from San Jose to a training camp in Texas. Then she'll go straight to Stuttgart, Germany, for the major precursor to the 2008 Games, missing at least the first two weeks of school.

"I guess I'll kind of be playing catch-up and doing things on my own schedule," Johnson said. "But I'm getting pretty used to that."