The two goals on either side of halftime were classic Wambach, the first coming on a powerful dribbling run and the second a towering header.
Two more goals for Wambach will put her in an elite club of U.S. women 100-goal scorers that includes Mia Hamm, Kristine Lilly, Michelle Akers and Tiffeny Milbrett.
The Americans will face Group A winner Canada Saturday at the Suwon World Cup Stadium.
June 19 in Suwon
USA 2 Italy 0. Goals: Wambach 41, 51.
USA -- Barnhart, Mitts (Chalupny, 66), Buehler, Markgraf, Cox, White (Heath, 46), Hucles, Lloyd (Wagner, 76), O'Reilly, Kai (Cheney, 46), Wambach (Rodriguez, 81).
Italy -- Picarelli, D'Adda (Guagni, 53), Schiavi, Perelli, Motta, Tuttino, Zorri, Boni (Iannella, 71), Gabbiadini (Fuselli, 46), Panico, Conti.
Referee: Alexandra Ihringova (England).