New Zealand were given a mighty scare by Argentina before Otere Black's late penalty gave them a 32-29 win in Calvisano.
The two teams were level at 15-15 with less than 20 minutes remaining before the Baby Blacks greater experience told and they ran in two tries in quick succession.
Argentina replied thanks to two scores from Benito Paolucci but they then collected a knock-on in an offside position from the final restart, allowing Black to steal the win.
It was the Pumitas who had the edge early on, and they led thanks to an Emiliano Boffelli penalty, while New Zealand then lost Vincent Tavae-Aso to a yellow card from the restart for taking the man in the air.
The Baby Blacks weren't affected though, and Mitchell Hunt pulled them level with a penalty, only for Argentina to make their territorial dominance pay with two more Boffelli three-pointers.
New Zealand hit back just before the half-hour with a length-of-the-field try from full-back Luteru Laulala, with great work from Sean Wainui and Harrison Levien in the build-up.
A drop goal from Matias Ferro gave Argentina the lead once more, but New Zealand showed their clinical side once again when TJ Faiane sliced through in midfield before sending Wainui over in the corner as the Baby Blacks led 15-12 at the break.
The second half was very open with chances at either end, but both sides struggled to take them. Argentina lost replacement Ignacio Calles to a yellow card for a high tackle, and he was soon joined in the bin by Laulala for offside as the Pumitas threatened to score.
Argentina were threatening though, still in the ascendancy in the territory battle, and after an infringement in a lineout, Domingo Miotti levelled the scores.
That's when the introduction of New Zealand's Super Rugby talent made the difference, with a searing break from Tevita Li setting up Te Toiroa Tahuriorangi for an easy score, converted by Otere Black.
Akira Ioane then sprinted over with a stunning run from inside his own half, showing all his pace to leave the Argentinian defence for dead for the bonus point.
Argentina responded though, scoring their first try through Paolucci from a drive at a lineout, before he repeated the trick after a monstrous rolling maul, with both converted by Miotti, only for Black to deny them.
Tries: Paolucci 2
Cons: Miotti 2
Pens: Boffelli 3, Miotti
Drop Goal: Ferro
Yellow Card: Calles
For New Zealand:
Tries: Laulala, Wainui, Tahuriorangi, Ioane
Cons: Hunt, Black 2
Pens: Hunt, Black
Yellow Cards: Tavae-Aso, Laulala
Argentina: 15 Matías Ferro, 14 Eugenio Achilli, 13 Emiliano Boffelli, 12 Bautista Ezcurra (c), 11 Julián Domínguez 10 Ignacio Albornoz, 9 Patricio Baronio, 8 Santiago Portillo, 7 José Deheza, 6 Benito Paolucci, 5 Ignacio Calas, 4 Ignacio Larrague, 3 Eduardo Bello, 2 Gaspar Baldunciel, 1 Nicolás Ocello.
Replacements: 16 Santiago Medrano, 17 Javier Díaz, 18 Ignacio Calles, 19 Vittorio Rosti, 20 Lucas Gasparri, 21 Lautaro Bazán Vélez, 22 Domingo Miotti, 23 Tomás Granella.
New Zealand: 15 Luteru Laulala, 14 Sean Wainui, 13 Jack Goodhue(c), 12 TJ Faiane, 11 Vincent Tavae-Aso, 10 Mitchell Hunt, 9 Harrison Levien, 8 Henry Stowers, 7 Mitchell Karpik, 6 Mitchell Jacobson, 5 Mitchell Dunshea, 4 James Blackwell, 3 Isileli Tu'ungafasi, 2 Steven Misa, 1 Aidan Ross.
Replacements: 16 Liam Polwart, 17 Tau Koloamatangi, 18 Atunaisa Moli, 19 Joshua Goodhue, 20 Akira Ioane, 21 Te Toiroa Tahuriorangi, 22 Otere Black, 23 Tevita Li.