After a series of underwhelming performances in the pool stage, where they finished second behind Fiji, this was a statement performance from France.

Back-rower Andy Timo scored the opening try after two minutes before 24-year-old Grandidier, who has an English father and a French mother, twice stormed in down the right.

Rayan Rebbadj added the conversions as France led 21-0 at half-time, even with talisman Antoine Dupont starting on the bench.

"We knew we had to start strong against a team like Argentina, they have been so good this season," said Grandidier.

"If we didn't put in a XXL performance against them we knew we would be in trouble."

Argentina narrowed the deficit to 21-14 through tries from Rodrigo Isgro and Marcos Moneta after the break, with Joaquin Pellandini kicking the extras.

Dupont, the irrepressible 15s superstar who is one of the poster boys of the Games, came on to add some nous as France played patiently to slow down their opponent's momentum.

Of course, Dupont also had to sprinkle some magic too. The scrum-half ran in a late try to seal victory and end Argentina's hopes of what would have been seen as a villainous comeback.

Grandidier was at the centre of the celebrations after the final whistle, high-fiving the gleeful supporters on the front row behind the dugout.

"We need to play without pressure which maybe let us down the first couple of games but we set the record straight," he said.