Wales crashed out of the Rugby World Cup after Emiliano Boffelli inspired an Argentina fightback that saw them win a thrilling spectacle 29-17 at Stade Velodrome.
The winners of Ireland's quarter-final with New Zealand will now play the Pumas next Friday in the Stade de France.
Warren Gatland's team had high hopes of reaching a third World Cup semi-final in the last four tournaments, but Argentina ripped up the form book after struggling to qualify from their pool.
Wales led 10-0 through a Dan Biggar try, conversion and penalty, only for Boffelli to wipe out that deficit with four penalties during a damaging spell either side of half-time.
Scrum-half Tomos Williams’ try, again converted by Biggar, put Wales back in front, but Pumas prop Joel Sclavi touched down and replacement fly-half Nicolas Sanchez claimed an interception try during the closing seconds. Boffelli converted both and then Sanchez booted a last-minute penalty.
It all rubbed salt into a gaping Welsh wound, although the Pumas were fortunate to see lock Guido Petti avoid sanction for a shoulder-led hit on Wales centre Nick Tompkins 16 minutes from time.
Referee Karl Dickson, who had taken over from an injured Jaco Peyper early on, awarded no card following television match official consultation, and Wales’ players looked perplexed.
Wales’ defeat meant the end of Biggar’s international career, having announced in August that he would retire from the Test arena post-World Cup.
Argentina had struggled to qualify from their group, but they made a bright start in perfect conditions by stretching Wales’ defence.
Boffelli, though, missed a 30-metre penalty chance and Wales responded through some fluency of their own and a determination to free prolific try-scorer Louis
Wales
Rugby World Cup
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Dan Biggar
Nick Tompkins
Tomos Williams
Emiliano Boffelli