Felipe Contepomi described Argentina's victory over Ireland as one of the most memorable moments of his career.
Contepomi plays his club rugby in Ireland with Leinster
The Pumas now play Scotland for a place in the Rugby World Cup semi-finals.
Contepomi, who kicked three penalties and a conversion, said: "It is a very proud moment for the team, for Argentina rugby and for the nation.
"People are talking about us as favourites for the quarter-final now, but if we are favourites we need to take on that responsibility."
Contepomi, who plays his club rugby in Ireland with Leinster, continued: "We need to work really hard and try to play our best game next week."
"I know people back home are following this like a football World Cup."
We showed the world we exist just as we said after the first match
Argentina had already secured a major scalp when they upset France in the tournament's opening game, and the win over Ireland meant they finished top of Pool D.
Coach Marcelo Loffreda added: "This is a very important step for Argentine rugby.
"There is huge merit in what this team has achieved, getting through the so-called 'pool of death' with a lot of authority.
"We knew Ireland were very dangerous and could destabilise our game so we had to keep control."
Captain Agustin Pichot said the Pumas had once again made the world take note of them as a team that should be involved in a major annual competition.
"We showed the world we exist just as we said after the first match," he said.