A superb late try from replacement Lucas Amorosino saw Argentina beat Scotland 13-12 on Sunday, putting one foot into the World Cup quarter-finals.
It was a gripping game at Wellington Regional Stadium as the Pumas came from behind to claim a priceless victory in the Pool B shake-up.
Argentina, who lost their opener to England but went on to beat Romania 43-8, now play Georgia in their final match while the Scots must conquer the unbeaten English to ensure a knockout spot.
Felipe Contepomi kicked two penalties and converted Amorosino's try for Argentina. Scotland's points came from a Chris Paterson penalty, a Ruaridh Jackson penalty and drop-goal and a second drop-kick from Dan Parks.
Scotland can have only themselves to blame for the narrow loss, with some poor decision-making and gifting too many turnovers to an Argentina side whose midfield defence was marshalled impeccably by outside centre Marcelo Bosch.
The match, played in pouring rain, also featured a litany of handling mistakes and the set-piece was a complete lottery.
For the first hour, there were predictable phases of play that featured strings of badly chased box kicks, non-productive pick-and-go's and inaccurate aerial ping-pong.
Paterson and Contepomi both missed early penalties before the latter finally got Los Pumas on the board after nineteen turgid minutes of rugby union.
Scotland's best attacking moment of the first period was squandered when Al Strokosch passed too early in a clear three-on-two down the left wing.
A similar chance was wasted shortly after when John Barclay opted to drive back infield with numbers outside.
With Argentina offering up little in attack, it was Scotland that went into half-time in the lead through two penalties in three minutes from Paterson and Jackson, the latter a beauty from 47 metres.
Bosch horribly skewed a drop-goal early in the second-half as Argentina tried to turn on the pressure, but the Scots went closest to a try.
Winger Max Evans, a livewire for Scotland, did well to collect his chip into the Argentinian 22-metre area but was well tackled by Rodriguez before offloading to Barclay.
From the ensuing ruck, captain Rory Lawson eschewed an overlap on the openside to play the blind and found a wall of beefy Argentinian forwards who promptly stripped him of the ball.
Paterson had a clear chance to extend Scotland's lead with a drop-goal, but the country's most capped player snatched at his effort and it went wide.
An infringement at a ruck and it was Contepomi's turn, the Pumas captain's penalty effort also drifting wide.
Contepomi made no mistake in the 63rd minute, however, nailing his second penalty after the Scottish front-row collapsed to draw the scores level at 6-6.
That lasted for only a minute as Jackson slotted over a well-taken drop-goal, as Contepomi's fifth penalty attempt went wide off the upright.
In a nail-biting finish to the error-riddled match, replacement fly-half Parks kicked a drop with practically his first touch to stretch Scotland out to 12-6.
But then woeful defence coupled by a fine finish saw replacement Amorosino skip through four tackles, turning a fairly innocuous play into a try. Contepomi showed nerves of steel to bag the conversion and take a 13-12 lead.
Parks' snatched left-footed drop-goal with a minute to play went wide, leaving Argentina in the driving seat for qualification.
Man of the match: Sean Lamont and Max Evans were both busy for Scotland, but for playing through the pain barrier Felipe Contepomi gets the nod. He also kicked the winning points.
Moment of the match: It had to be Lucas Amorosino's dash of magic down the right-hand touchline. He weaved in and out to beat a handful of desperate Scotland defenders
Villain of the match: Whether it was the Pumas doctor or Juan Matrin Fernandez Lobbe himself who made he decision, but the number eight should not have continued with such a knee problem. More sense is needed in such situations as he could well have done more damage.
Pen: Contepomi 2
Pen: Paterson, Jackson
Drop: Jackson, Parks
Argentina: 15 MartÃn RodrÃguez, 14 Gonzalo Camacho, 13 Marcelo Bosch, 12 Felipe Contepomi (c), 11 Horacio Agulla, 10 Santiago FernÃ¡ndez, 9 NicolÃ¡s Vergallo, 8 Juan Martin Fernandez Lobbe, 7 Juan Manuel LeguizamÃ³n, 6 Julio Farias Cabello, 5 Patricio Albacete, 4 Manuel Carizza, 3 Juan Figallo, 2 Mario Ledesma Arocena, 1 Rodrigo Roncero.
Replacements: 16 AgustÃn Creevy, 17 MartÃn Scelzo, 18 Mariano Galarza, 19 Genaro Fessia, 20 Alfredo Lalanne, 21 Lucas Gonzalez Amorosino, 22 Juan Jose Imhoff.
Scotland: 15 Chris Paterson, 14 Max Evans, 13 Nick De Luca, 12 Graeme Morrison, 11 Sean Lamont, 10 Ruaridh Jackson, 9 Rory Lawson (c), 8 Kelly Brown, 7 John Barclay, 6 Al Strokosch, 5 Jim Hamilton, 4 Richie Gray, 3 Geoff Cross, 2 Ross Ford, 1 Allan Jacobsen.
Replacements: 16 Dougie Hall, 17 Alasdair Dickinson, 18 Nathan Hines, 19 Richie Vernon, 20 Mike Blair, 21 Dan Parks, 22 Simon Danielli.
Referee: Wayne Barnes (England)
Assistant referees: Nigel Owens (Wales), Chris Pollock (New Zealand)
Television match official: Shaun Veldsman (South Africa)