The bronze playoff kicked off at 4pm at the National Football Stadium under fine weather conditions in front of a sold out Port Moresby crowd.
Both teams remain scoreless at half-time.
Japan, in white and blue uniform, had more ball possession and made more attempts than their opponents.
The Asian side is led by top goal scorer and captain forward, Yuka Momiki.
USA, in black and blue, are led by captain Mallory Pugh.