The USA kept up their record of not conceding a goal under Emma Hayes but were held 0-0 at home by Costa Rica.
Visiting goalkeeper, Noelia Bermúdez, frustrated the Americans with a dozen saves.
Sophia Smith came closest to a breakthrough but hit the post before Bermúdez made the save, as Costa Rica avoided defeat against the US for the first time in 18 meetings.
USA begin their Olympics fixtures on 25 July versus Zambia , with Germany versus Australia the other Group B game.
Canada were 1-0 winners over Nigeria in Spain, Jordyn Huitema finding the net in the 20th minute. The Canadians also kick off their Olympics next Thursday, New Zealand their first Group A opponents while Colombia face France. First up for Nigeria in Group C is Brazil, with Japan taking on Spain.
Japan and Colombia drew a behind-closed-doors game in France 1-1, a late exchange of goals saw Mayra Ramirez equalise for the Colombians.
Fernanda Araya hit a hat-trick as Chile won 5-0 against Paraguay
Other friendly international results:
Belize 0-2 Bermuda
El Salvador 3-0 Peru
Russia 0-0 North Korea
Senegal 2-0 DR Congo
Singapore 9-0 Macau
Tunisia 1-0 Botswana
