Shawn Johnson's mother enrolled her in gymnastics class out of fear more than anything else. At least at the gym there were mats, foam pads and coaches to catch the little daredevil.

Back home, Johnson had climbed out of her crib before she could walk. As a toddler, she liked to stack toys or furniture and jump off. At the park, Johnson's favorite thing was running pell-mell down a steep set of concrete steps.

"She was a train wreck waiting to happen," said Teri Johnson, Shawn's mother.

Now Johnson's favorite thing is sprinting down a runway, launching off a springboard, pushing off a vault and flipping two and a half times through the air before sticking a perfect landing.

The sight of Johnson's acrobatic Yurchenko vault could become one of the highlight images of the Beijing Games, which begin Friday. So could the sight of Johnson standing atop the medal podium, her gold medal, white teeth and blond ponytail glinting in the camera lights.

Not only is Johnson from "America's heartland" — West Des Moines, Iowa — where June's floods damaged the gym where she trains, but she's the all-American girl who stayed in public school so she could go to the prom and attend classes with her friends rather than take the home school route chosen by most elite gymnasts so they can spend more hours in the gym.

Get ready for lots of Shawn Johnson. She is poised to ascend to the cereal-box throne previously occupied by Carly Patterson and Mary Lou Retton. She could become the most dominant all-around champion since Nadia Comaneci. And she could lead the U.S. to its first team gold since a lame Kerri Strug vaulted the Magnificent Seven to the top in 1996.

Johnson, 16, won the 2007 world individual title as the U.S. edged the Chinese. She has a rare combination of power on vault, personality on floor exercise, fluidity on balance beam and daring on uneven bars. At 4-8, 90 pounds, she's more bounce than ballet.

"Shawn's style is 'Ready, set, go!"' said former world champ Kim Zmeskal-Burdette, now a coach. "I remember the first time I saw her and saying, 'My God, this kid is crazy.' She'd run down the middle of the floor and do a double full or hop onto the beam."