France coach Jacques Brunel admitted a sense of relief after his side held off Argentina's superb second-half comeback to win their World Cup Pool C opener 23-21 at Tokyo Stadium.
rance were seemingly in total total control at 20-3 following tries from Gael Fickou and Antoine Dupont, with 20-year-old fly-half Romain Ntamack converting both before kicking two penalties.
The Pumas, though, made a breakthrough early in the second half when Guido Petti Pagadizabal bundled over from a line-out, before replacement hooker Julian Montoya touched down.
Penalties from Benjamin Urdapilleta then saw Argentina move ahead, before Camille Lopez's drop goal saw France edge through the closing stages.
"We are relieved of the result, but not totally satisfied with the performance," Brunel said at a press conference.
"We have shown hesitations, gaps. It must be rectified to go further in the competition.
"There were deficiencies shown in the second period after we had controlled the first half well.
"We had difficulties in the tackle and the Argentines came back in the game too quickly, even if we had expected it.
"We still have work to do, but we know what to focus on so that is good."
Ntamack followed father Emile in playing for France at the World Cup.
The fly-half said: "It was a really, really tough game. We knew we'd face a really strong Argentina team and after a stressful game we're happy to have won here."
Argentina had been aiming to repeat their shock victory over Les Bleus in the opening match of the 2007 World Cup in France, where they went on to reach the semi-finals.
Pumas head coach Mario Ledesma was left to reflect on what might have been, with Urdapilleta's late, long-range kick dropping just the wrong side of the posts.
"We missed opportunities in the first half and that second half, (it was a) very good second half," he told reporters.
"We didn't do anything in the first half - defended badly and didn't attack well, lost every ball into contact, so just not doing what we've been doing for a while now.
"In the second half we created many opportunities, scored and also just missed two points (near the end)."
Pumas captain Pablo Matera is determined the squad will bounce back.
"I feel very bitter because we can win this kind of match," he said.
"We gave a big advantage to the opponent. There is no room for more mistakes, we have three more important games."