The USA has now won three consecutive games against the Japanese after tying the three previous matches.
"I was really happy with the performance," said U.S. head coach Greg Ryan. "I thought we defended really well. Japan is very quick, skillful and creative, and broke us down in the second half, but overall I thought we defended very well. I was really happy with how aggressive we were in attacking and really going after them."
July 28 in San Jose
USA 4 Japan 1. Goals: Boxx 17, own goal 41, Lilly 55, Wambach pen. 72; Nagasato 79.
USA -- Solo, Rampone, Whitehill, Markgraf, Lopez (Ellertson, 75), Boxx (Hucles, 85), Osborne (Lloyd, 61), Chalupny, Tarpley (Kai, 70), Wambach, Lilly (Jobson, 83)
Japan -- Fukumoto, Iwashimizu (Yamaguchi, 86), Isozaki, Sakai (Ando, 12; Sakaguchi, 67), Toyodal, Miyamoto, Miyama (Yanagita, 58), Sawa, Kinga (Yano, 75), Arakawa (Nagasato, 67), Ohno.
Referee: Jennifer Bennett.