GREENWOOD VILLAGE, Colo.—On Tuesday, the Cherry Creek High School girls' swim team will lose for only the 19th time out of some 400 meets over 38 years.

It's a near certainty for this suburban Denver squad, whose speediest girls have no hope of matching their swiftest opponent, Missy Franklin, the 17-year-old star of Regis Jesuit High School and, oh yeah, the bubbly five-medal winning heroine of the London Olympics.

"It's...