Tameka Butt scored in the 67th minute and Australia beat the United States for the first time in the 28-game series, 1-0 in the Tournament of Nations on Thursday night.
The Matildas also snapped the Americans' four-game winning streak.
Just moments after Butt's goal got past goalkeeper Alyssa Naeher, Carli Lloyd blasted a cross from Megan Rapinoe at Australia goalkeeper Lydia Williams, who made a fantastic save. Lloyd had another chance that sailed just over the net.
Japan and Brazil played to a 1-1 draw in the tournament's opening game in the afternoon at CenturyLink Field.
Each of the four teams in the tournament is in the top 10 of the FIFA rankings. The top-ranked United States went into the game with a 25-0-2 record over the seventh-ranked Matildas.
Rapinoe, who plays for the NWSL's Seattle Reign, had a good chance early on in the game but the Americans were unable to break through. Rapinoe has 12 goals to lead the NWSL in scoring this season.
The Matildas have been on the rise of the past several years, with quarterfinal appearances in both the 2015 World Cup and the Olympics last year.
Following the stop in Seattle, the tournament shifts to San Diego on Sunday before wrapping up at the StubHub Center in Carson on Aug. 3.