Defeat to the Pumas would see injury-depleted Ireland drop into the third tier of seeds for next month's draw for the 2015 World Cup, which is based on the IRB rankings system.
The reality of competing in a pool also containing two major rivals would cast a shadow over Irish rugby for the next three years and they could have to wait until 2019 for redemption.
A mixed autumn based on defeat to South Africa and an easy victory over Fiji would be deemed a success if Argentina are dispatched and Foley knows what is on the line.
"This is probably the biggest game I've been involved in during an autumn series," the defence coach said.
"It has ramifications across the board for the next three years so it's very important.
"But it's still 80 minutes of rugby so we need to get our preparation right, make sure the boys get a good night's sleep and not worry too much about it.
"If we have a good mentality on the weekend we should be okay. If you start worrying about results you'll miss what's in front of you.
"Judging by what we've done for the last two weeks, it's pretty spot-on where we are at the moment.
"Preparation is going well, guys are turning up and willing to put their bodies on the line.
"There isn't much being held back in training and there isn't much being held back in preparation.
"We all know what the consequences of the weekend are, but the most important thing is that we make sure we get our processes in place."
Argentina are equally desperate to safeguard their place in the top eight and will provide hard-nosed opposition in what will be a tense afternoon at Lansdowne Road.
Former Ireland flanker David Wallace recently described the Pumas as the most physical team in Test rugby, but Foley insists his side are equally rugged.
"A lot of guys within the squad and have played in France, so when you play in France it's pretty similar," he said.
"You play French sides and they're big men, they will hit you and you will get hurt, and you need a certain degree of toughness about you.
"These guys wouldn't be in the Irish squad if they hadn't had that level of toughness that they show for their provinces.
"So we're pretty confident that we can handle the physical side of the game."
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