The star midfielder arrived in Buenos Aires on Tuesday morning and spoke to the media ahead of Friday's World Cup qualifier with Chile, which is followed by a Venezuelan test
Alejandro Sabella's men are set to lock horns with Chile on Friday and Venezuela four days later.
The Paris Saint-Germain star has five goals this term for his club as they sit in first place in Ligue 1, three points ahead of Montpellier, Lyon and Toulouse.
While his club have not lost a league game since matchday one, Pastore still feels the sting caused by the lack of success of the national team after being eliminated in the quarter-finals of the 2010 World Cup and 2011 Copa America.
"The failures must be left behind," Pastore told the media. "We've had failure after failure."
With a new coach leading the country and with an abundance of talent in the squad, the former Huracan man has hope.
"We have a number of important players and we have to start off winning to earn an advantage in the first encounters [of qualifying]," Pastore said.
"The upcoming games are very tough and complicated."
Argentine face Chile on Friday at 2310 GMT.