With their lightning quick passing and slick combination play, the Japanese may well have a grip on the future of the game.
The physical, sweeping game of the Americans stands in sharp contrast with the close, possession-oriented game of Japan, turning Sunday's match into an intriguing clash of styles.
The United States beat Japan in two pre-World Cup friendlies but it will count for little in the final.
United States captain Christie Rampone says ''they're a different team here in the World Cup. It brings a different level.''