Samoa has one win under their belt and sits second in Pool D, behind England.
The Pacific Islanders eventually ran out 43-10 winners over the Chileans, but coach Vaovasamanaia Seilala Mapusua said they could not afford a similarly sluggish start on Sunday against the Pumas, who have twice reached the World Cup semi-finals.
"The boys realise that we're in the tournament now; we've arrived at the party and there are no second chances," Mapusua said.
"So this week in the whole squad there's been a real lift and an energy and we know that we've got a huge game against the Pumas on Friday.
"We won't be short of motivation."
Manu Samoa have named a strong lineup to face Argentina in Saint Entienne on Saturday morning, Samoa time.
But there is no Lima Sopoaga, who has been ruled out of the game because of a minor injury.
Chris Vui will captain the side.
Ray Niua has joined the squad as an injury replacement for hooker Luteru Tolai.
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