Dan Parks was the hero again as Scotland came roaring back from 13-6 down to become the first side ever to beat Argentina here, the fly-half landing six penalties and two drop goals.
He could even afford some rare slip-ups as Scotland dominated the second half and the home side were made to pay for persistent infringement at the breakdown. But it had looked ominous for the tourists early on when errors saw them concede tries to Gonzalo Tiesi and Juan Manuel Leguizamon.
Scotland had a miserable record against the Pumas, losing eight of the last nine meetings, including at Murrayfield in November in Andy Robinson's first defeat in charge. Argentina, who are in Scotland's World Cup pool next year, had never lost in their seven previous games in Tucuman.
Max Evans lost the ball in the tackle to allow Felipe Contepomi to feed Tiesi, who ran in unchallenged. Then Horacio Agulla claimed a Contepomi chip to the corner and offloaded for Leguizamon.
Parks (pictured) kicked a drop goal on the stroke of half-time to cut the deficit to a point, and in the second half the Pumas made errors in their own 22, giving away a penalty from which Parks was able to put Scotland ahead for the first time.
Then he kicked a 48-metre penalty followed by a close-range drop goal to put Scotland eight points ahead.
Contepomi cut the deficit with a long-range penalty but yet more Argentinian infringement allowed Parks to wrap up a superb victory. The two teams meet again next Saturday in the coastal city of Mar del Plata.
South Africa strolled to 42-17 victory over France at Newlands in Cape Town. The tourists never recovered from an opening quarter in which the world champions went 17-0 up.
Argentina: Rodriguez, Borges (Amorosino, 47), Tiesi, Fernandez, Agulla, Contepomi, Lalanne (Figuerola, 78), Roncero, Ledesma (Creevy, 68), Scelzo (Ayerza, 44), Carizza, Albacete, Fessia, Leguizamon, Fernandez Lobbe.
Scotland: Southwell, Evans, De Luca, Morrison, Lamont, Parks, R Lawson (Blair, 60), Jacobsen, Ford (S Lawson, 76), Low, Hamilton, Kellock, Brown, Barclay, Beattie (Strokosch, 60).
Referee: D Pearson (RFU).