She is unbeaten, unreal, and wonderfully unaware.

"I guess I run because I'm not good at anything else," Sarah Baxter says with a tiny grin.

She hasn't lost a cross-country race in the three years of her Simi Valley High career, yet she once got lost while leading a race on her home course.

"She was supposed to go left, she went right, and everyone was screaming and jumping to get her attention," recalls Jessie Ellis, a Pioneers assistant girls' cross-country coach. "A funny story, but there are a lot of funny stories about Sarah."

She is a three-time state champion and a two-time high school national champion after last weekend's victory in the Nike Cross Nationals in Portland, Ore. Yet her teammates say her most memorable move occurs before every race, when, at the starting line, she breaks into a dance they call "The Baxter Boogie."

Says Baxter: "Oh, c'mon, I'm just shaking it out."

Says teammate Olivia Rosellini with a giggle: "She's pretty quirky."

This fall she ran the fastest 5K girls' time in the 64-year history of the course at the Mt. San Antonio College Invitational in what one expert called "the greatest high school performance ever." She later set the state meet course record in Fresno. But her teammates says she's more amazing when she hangs back with them, because, in the middle of a long run, while everyone else is breathless, she'll start crooning loud renditions of Journey or Elton John tunes.

Says Rosellini: "Out of nowhere, she starts singing, 'Don't stop believin'…' and we're like, what?"

Says Baxter: "That's why I like to run with them. When I run by myself, I'm left to my own thoughts, and that's not always pretty."

She doesn't have much choice on that "run by myself" part. As arguably the best girls' cross-country runner in the country, the 16-year-old junior often competes by herself, running far in front of the pack with a 30-0 record that has rarely even been challenged.

She is so good, beaten opponents ask for her autograph. She is so fast, she can finish a race, towel off, and return to the course to cheer on her teammates.

"We'll all be kicking toward the finish and she'll be standing there all rested and waiting for us," says teammate Sarah Riggs. "It's just unnatural."

What is unnatural is how this 5-foot-6, 100-pound girl with long blond hair and a shy smile handles the pressure. She has never lost, so she's never allowed to lose. Other teams and athletes can have bad games, bad months, even bad seasons if they can figure it out during the playoffs — hello, Lakers — but Baxter can't even have a bad 15 minutes.

"It's kind of scary," she says. "I try not to think about it."

Every time she steps onto one of those winding dirt paths, everyone is...