Argentina overcame a disastrous start on Saturday afternoon to beat Wales 29-17 and advance to the World Cup semi-final.
Argentina boss Michael Cheika said in the prelude to the clash at the Vélodrome in Marseille that his side would be the underdogs.
His prediction was borne out. They played like newborn puppies during the first half-hour.
Wales fly-half Dan Biggar broke the deadlock after 14 minutes when he touched down under the posts.
The veteran added the two points for the conversion and then kicked over a penalty to establish a 10-0 advantage. But Wales botched several line-outs near the Argentine line that should have brought more points.
And just before half-time, Emilano Boffelli made them pay for their lack of precision.
He converted two penalties for Argentina, and just after the restart the 28-year-old added another two to take his side in front for the first time.
Lead
Tomos Williams scored for Wales to help to establish a 17-12 advantage.
That was erased when Joel Sclavi drove over with 12 minutes remaining.
As Wales pressed for the try or penalty to give them victory in the final minutes, Sam Costelow's pass to Williams was intercepted by substitute Nicolas Sanchez who ran clear to touch down under the posts.
He converted and then added a penalty as part of his 10-minute star turn to adorn a famous victory at the same venue where Argentina drooped against a 14-man England side on 9 September.
But wins over Samoa, Chile and Japan allowed them to finish as runners-up in Group D.
Next stop Stade de France
"Obviously we’re incredibly disappointed," said Wales boss Warren Gatland.
"But I don’t want to take anything away from Argentina in terms of their performance. They were a tough team to put away and they hung in there with the fight, kept going.
"They deserve a lot of credit for the way that they played today. For us we weren’t quite at our best, but we had opportunities to win the game."
Next Friday at the Stade de France, Argentina will play New Zealand, the winners of Saturday night's quarter-final against Ireland.
Cheika acknowledged his players would not be favourites in that match either.
"We are just thrilled to be going to the Stade de France as we haven't had a chance to play there yet," Cheika added. "We'll be giving it our best.
"The players have worked really hard and I think that hard work showed at the end of the game. They wanted to fight for it, they wanted to earn it."
