It was Michelsen, who has been terrific through the tournament, who fittingly scored the winning goal last night.
She deflected an Ella Gunson drive from a penalty corner into the Argentine net, and that came a minute after the Black Sticks had equalised after giving away a goal in just the second minute.
Defender Brooke Neal scored from a penalty corner to shake the Argentines; Michelsen's strike rocked not only the crowd but the South Americans' too.
They then held off a series of Argentina attacks through a largely one-sided final quarter, and although it wasn't always calm and clever defensive work, it had tons of heart and the Black Sticks got a fantastic reward.
The third quarter did it for New Zealand, during which they had eight shots on goal to three and the bulk of the possession and got their goals.
By the end, Argentina had made 30 circle penetrations to 12 by the Black Sticks. So step forward experienced goalkeeper Sally Rutherford, who had a memorable night.
"To have her back there and calm everyone down to make those key saves, she's unbeatable," an admiring Neal said of the keeper.
The Black Sticks will next face either the United States – who beat them 3-1 despite the New Zealanders having much the better of the contest statistically in their final pool game on Monday – or England, who square off in their quarter-final tonight.
South Korea caused an upset in the first quarter-final last night.
Having drawn 3-3 with sixth-ranked Germany, the Koreans were far superior in the penalty shootout, taking their chances impressively against a tentative German side to win it 3-1.
The Koreans linked arms and danced delightedly in a circle after the final goal.
World No 1 Netherlands play China in the final quarter-final tonight.
