25. Alicia Sacramone

Gymnastics
United States
Age: 20

If you're a female gymnast in the U.S., no one's opinion matters more than that of Martha Karolyi, the national team coordinator and Olympic team gatekeeper. And of Sacramone, a champion on vault and floor exercise, Karolyi says, "it would not be the same team without Alicia." The effervescent Brown undergrad provides both motivation and inspiration for team USA, rallying spirits during the tension-filled team meets, as she did at last year's World championships. Her rousing floor routine pulled the U.S. to a gold. They'll need that girl power boost going up against a talented Chinese team on its home turf.