Mateo Carreras scored a hat trick of tries on Sunday afternoon as Argentina moved into the quarter-finals at the World Cup after a pulsating 39-27 win over Japan.
The Group D clash had been recast as a knockout game with both sides able to advance to a showdown against the Group C winners Wales.
Santiago Chocobares scored with Argentina's first attack of the game at at the Stade de la Beaujoire in Nantes. Emiliano Boffelli added the two points for the conversion.
Japan drew level with a vignette of scintillating individual brilliance. Lock forward Amato Fakatava collected the ball on the left touchline, nimbly lobbed it over the Argentina defenders, lapped up the kind bounce and rampagned on over the try line. Rikiya Matsuda added the conversion to level the game.
Carreras' first of the encounter on the left wing recaptured the lead for the South Americans but Boffelli could not add the two points.
Battle
He was more accurate five minutes later though when he converted a penalty to take his side to 15-7.
But back came the Japanese through Naoto Saito and Matsuda's conversion left the game finely poised at 15-14 to Argentina at the break.
The see-saw tussle continued in the second-half.
Carreras scored his second try to extend his side's lead to 20-14 and after the conversion, Matsuda knocked over a penalty to reduce the deficit to 22-17.
Lomano Lemeki's drop goal brought Japan within two points at 22-20 but Boffelli added a try and the conversion took Argentina nine points clear.
Return
But the Japanese came back again. Jone Naikabula with the try and and Matsuda's conversion made it a two-point game again at 29-27
But before the Japanese could build momentum or any pressure, Carreras added his third of the game.
The conversion restored the nine-point gap and Nicolas Sanchez converted a penalty in the 74th minute to take the game away from Japan and set up a match in Marseille next Saturday afternoon.
On Sunday night in Group C in Toulouse, Fiji can reach the last eight for the first time since 2007 with a point against Portugal.
"I've watched them since we knew we would be playing them," said Fiji coach Simon Raiwalui. "They play a great brand of rugby, with a good spirit.
"We know it will be a really tough match. We really want to perform to the best of our ability and if we do that, the result will take care of itself."