Pearce said the American's first goal had been a wake-up call, prompting them on to the front foot.
"We were under the impression we were going to play Australia ... but all we were thinking about was winning," said the North Harbour striker with 74 caps lauding the Kiwi defence for preventing USA from equalising.
Slipping on the gold medal and keeping the silverware in the cupboard for another year is on the agenda tomorrow evening. Australia and Argentina have won the first two crowns.
Asked what it would take to dismantle the stubborn Japan defence, Pearce said they hadn't seen much of the earlier game while warming up but they were intending to scout their game plant tonight.
The pistons in the hosts' engine room will have to working with more intent and purpose than it did tonight.
"It'll really be interesting to see if they have changed things up. They have beaten Australia so they have done well," she said, adding what the Sticks do tomorrow would matter more than what the Japanese produce.
It was characteristically another slow start from the Mark Hager and Sean Dancer's women as the tourists went for the jugular from the opening flick.
That urgency was rewarded in just the third minute when Team USA drew first blood from a penalty corner through Caitlin van Sickle after captain Melissa Gonzalez served it up and Katelyn Falgowski deftly trapped for a 1-nil lead.
Captain Olivia Merry and her troops were stung into action to yield two PCs with Pearce laying it up, Merry trapping but 150-capped Rose Keddell finding no cigar both times.
The hosts came close again in the 10th minute when Kelsey Smith threaded a withering pass from the left flank but, amid the crowd's "Ooh!", Merry couldn't bring the beast to heel on the far post as the opportunity went begging.
With two minutes left in the spell, USA goalkeeper Lauren Blazing's foot was the difference as she stared down the barrel at Merry's wormburner in the one-on-one standoff.
But the concoction of patience and pep talk from Dancer worked magic as the Kiwis equalised 1-all from Pearce in the 23rd minute via a field goal after Merry toiled to put the ball into the stock exchange.
In fact it worked like a dream as predators turned prey with the Black Sticks mounting waves of attack and asking the Team USA cavalry a lot of questions.
A diligent sweeper, Brooke Neal, having a prominent presence in the entire game, deservedly scored from one of a rash of PCs in the 28th minute.
Pearce stuck to her routine, Erin Goad brought the ball to a stand still before Neal rifled it into the top of the net past Blazing and her wall of red.
With halftime approaching Goad skied her effort over the crossbar from 5m out and dead in front of the goalmouth after another Pearce pass.
The New Zealanders made all the play for the best of the third quarter but, regrettably, couldn't convert numerous chances, including PCs, to extend their lead although Hager's mantra of going for the jugular and consistency must have been ringing in their ears.
In the 39th minute, the Americans left a calling card to remind the Kiwis their game wasn't over until they stopped making visits to their house. A tireless Erin Matson clipped the left upright, much to the relief of veteran goalkeeper Sally Rutherford.
It was Team USA coach Janneke Schopman's turn to bite her bottom lip as Merry threaded a ball through a porous defence but Pearce, pirouetting with the ball, miss hit from inside the D with just keeper Blazing to beat in the 41st minute.
Rachel McCann, having received a bouquet of flowers akin to Keddell for her 50th appearance for New Zealand, latched on to the deflection but the ensuing swipe shot from an oblique angle went screaming past the face of the goalmouth.
Japan, already in the final by virtue of three wins and nine points, watched from the balcony with bated breath as they cheered for an American equaliser, perhaps preferring a final against the Hockeyroos to negate the impact vociferous parochial home fans tomorrow.
The final quarter saw the Americans showing more intent in not letting the Kiwis bully them.
Matson, Kathleen Sharkey and Jill Witmer were on their hands and knees at the coal face but to no avail.
The Black Sticks scrambled in Japan fashion to prevent a stalemate while a tired-looking Team USA were guilty of trying to go through the spine of the turf rather than going out wide to create holes in the compact white wall.
Coach Schopman was happy with her troop's start but felt they lost their way in the second spell when New Zealand levelled.
"We were unable to keep possession and we were struggling a little but we were able to come back in the final quarter to create some pressure and some opportunities."
Schopman said they were mindful of how quick the hosts were and itching to go forward.
"We gave them too many opportunities today," she lamented, also thinking they were playing Japan.
Schopman said their big goal was the impending World League 3 from next month so they appreciated fine tuning their systems from the eight games in the tourney and two before that in Christchurch.
"For me, with every game, it becomes more clearer on what details we need to focus on to the World League 3, which is our most important tournament this [northern] summer."
Schopman said while they had taken account of their individual brilliances, Team USA needed to work as a collective so that everyone could excel.
She had noticed the Black Sticks had incrementally grown in this tourney but the Hockeyroos were different although they also were keen to use their numbers for a forward thrust.
"It's great to be here and have such a welcoming community," said the former Netherlands international defender who turns 40 on April 26.
