Russia slipped to their third straight defeat in Beijing
The United States and Hungary are through to the semi-finals of the women's water polo competition.
The US will play either Australia or China while Hungary will play either Italy or the Netherlands.
The Americans reached the last four by handing European champions Russia, ranked third in the world, their third straight defeat, winning 12-7.
"There was no way in their thinking process Russia were going to be in that position," said US coach Guy Baker.
In other matches at Yingdong Natatorium, Hungary beat Greece 10-4, Australia edged past the Netherlands 10-9 and Italy squeezed past China 10-9 thanks partly to Elisa Casanova's four goals.
Casanova, who broke her nose in Italy's first game, played a second consecutive match with a protective mask that limits her eyesight and breathing.