Ireland assistant coach Anthony Foley admits the stakes are impossibly high in Saturday's showdown with Argentina at Aviva Stadium.
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.
"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."
A mixed autumn based on defeat to South Africa and an easy victory over Fiji would be deemed a success if Argentina are dispatched.
But the Pumas 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 them as the most physical team in Test rugby, but Foley insists his side are equally rugged.
"These guys wouldn't be in the Irish squad if they hadn't had that level of toughness that they show for their provinces," he said.
"So we're pretty confident that we can handle the physical side of the game."