The U.S. looked far from gold-medal form, but did enough against a dangerous Japanese side to pick up a much-needed three points in Group G after dropping its opener against Norway.
The Americans created a host of scoring opportunities, but were only able to capitalize in the 27th minute, when Lloyd volleyed a cross from defender Stephanie Cox just under the crossbar.
The United States, which plays New Zealand in its final group match on Tuesday in Shenyang, has three points in the group. Japan has one point, and faces Norway next in Shanghai.
