The game was extremely intense as both the United States and Australia went scoreless through seven innings, but in the end it was Amanda Chidester who came through for the Americans with a two-RBI walk off single in the eighth inning to lift Team USA to 4-0.
Monica Abbott pitched seven innings of shut out ball before letting up a run to Belinda White on a bases-loaded walk.
Abbott recovered the next batter, striking out Tarni Stepto to give the Americans the chance to end the game.
Watch all the action from the Tokyo Olympics live on NBC
While the U.S. allows its first run in Tokyo, the bats stepped up to lead them to victory.