In comparison to yesterday's performance, the Black Sticks were on fire from the first whistle in game two, keeping up their intensity for much of the match to place the world No3 Argentinians under continual pressure.
There was early excitement for the home crowd when Pearce drew goalkeeper Belen Succi to the top of the circle, tapping the ball easily around the Argentinian. But the Kiwis' lead didn't last long as the visitors twice found the net, first through Maria Granatto and then Noel Barrionuevo's unstoppable drag flick.
The home side headed to the break behind but found their way back into the match straight after halftime, with Flynn applying a decisive deflection from a penalty corner. Then, with the clock winding down, Merry slotted home a trademark penalty corner flick to put the Black Sticks in the lead for good.
"Penalty corners were definitely a work-on from our last game and so to score from penalty corners today was pleasing," said Merry, who is due to play her 100th test in the series' final game on Friday.
There was still time for Argentina to hunt for a late equaliser but, in the nervy final moments of the match, the South Americans couldn't convert from a penalty corner of their own right on fulltime.
The teams now travel to Nelson for Tuesday afternoon's third game, before heading to Christchurch for the final clash on Friday night. Both matches will be streamed live and exclusive on nzherald.co.nz.