France and Argentina served up a classic to launch Pool C and the result was in doubt until the final minute, when a long-range penalty from full-back Emiliano Boffelli missed by inches.
France had turned on the style to take a 20-3 lead at half-time in Tokyo, scoring two beautifully worked tries through Gael Fickou and Antoine Dupont. Yet Argentina swarmed all over them in the second half, even clawing themselves into a 21-20 lead for a couple of glorious minutes.
The match was a stark contrast between the respective kickers, Romain Ntamack, and Nicolas Sanchez. Ntamack kicked his first four attempts; Sanchez was withdrawn after an hour.
After a tight, error-strewn opening, Argentina edged in front in the 15th minute with a Sanchez penalty. Sanchez, the leading points scorer at RWC 2015, had missed narrowly from distance two minutes earlier, but made no mistake after a barrelling run from Tomas Lavanini put the French on the back foot and they went offside.
If this youthful French side was alarmed, it did not show and they hit back with two tries in five minutes. First, Damian Penaud pinned Argentina on their left, and the ball was worked to the far corner for Fickou to touch down.
Penaud was again involved when scrum-half Dupont rounded off a magnificent move, featuring numerous changes of direction and clever offloads, by nipping over in the right corner, above. It was Dupont's fourth try in his past five matches.
On both occasions, 20-year-old fly-half Ntamack added difficult conversions with nerveless authority. Ntamack, the son of Emile Ntamack, who played in the 1999 final for France, added a much simpler penalty for a high tackle to extend France's lead to 14 points on the half-hour and another in added time.
The Pumas needed an early response in the second half and found it when second-row Guido Petti scored a converted try from the back of a lineout. Suitably fired up, they bombarded the French line and in the 54th minute the same gambit - a lineout followed by a driving maul - ended with Julian Montoya touching down.
On the hour, Sanchez's replacement, Benjamin Urdapilleta, slotted over a penalty and it was back to 20-18.
Without a point in the second half, France were clearly rattled, the fluency of the first half having deserted them. The last thing they needed was for Sebastien Vahaamahina to concede an extra 10 metres for shoving after a penalty. Urdapilleta stepped up and, unbelievably, Argentina were ahead by a point.
But there was still a sting in the tale. Replacement Lopez, with just about his first touch, launched a drop goal from 30 metres which crept over the bar, but only just.
-Story derived from RugbyWorldCup.com