Ireland's women will meet China in Thursday's quarter-finals of World League 3 after achieving their first ever win over the USA.
Megan Frazer's goal just before half-time and Anna O'Flanagan's late goal secured Ireland's 2-0 superb victory in Valencia on Tuesday.
The Irish had to defend heroically as the US forced eight penalty corners.
Germany would have won the group with victory over South Africa later in the day, but that match end 0-0.
Ireland, therefore, progressed to the last eight as Pool B winners to face a Chinese side who have lost three of their four games in Spain.
The semi-finalists teams in the tournament will earn automatic berths to next year's Rio Olympics although a top-six finish in Valencia could prove enough to book Ireland's place in Brazil.
Ireland have never qualified for an Olympic Games in either men's or women's hockey.
The Irish are ranked 14th in the world while the USA are currently rated fifth.
Frazer went close for the Irish early but the Americans were on top before Gillian Pinder set up the skipper to score a minute before half-time.
Cliodhna Sargent produced a brilliant block to deny Melissa Gonzalez as the Irish held out despite Shirley McCay's sin-binning in the third period.
Irish keeper Emma Gray then brilliantly denied US strikers Rachel Dawson and Lauren Crandall before Frazer's breakaway set up O'Flanagan to score Ireland's second goal a minute from time.
The Irish had lost three times to the USA in warm-up games over the last month but skipper Frazer insisted the result was "not a complete surprise".
"All credit to our coaching staff. They put together a fabulous tactical plan and we executed well. We had belief from the beginning," insisted Frazer.