The winners will be guaranteed a place in the second tier of seeds for next month's 2015 World Cup draw, which is based on the IRB rankings.
The losers will slip out of the top eight and potentially face a pool containing two heavyweight rivals.
Heaslip, who will be leading the Test team for the second time, has stressed the importance of forgetting the possible ramifications of the climax to Ireland's Guinness Series.
"In the greater scheme of things it's an important game, but for us it's like any other match," Heaslip said.
"We've all played in big matches like Heineken Cup finals and internationals.
"We just have to treat it like we treat every game and chance that we get.
"Argentina will be a lot more organised because of the time they have together now.
"They have a big, physical pack and their backs aren't afraid to play either."
Ireland have made one change to the side dispatched by South Africa with Craig Gilroy replacing Ulster colleague Andrew Trimble on the left wing.
The uncapped 21-year-old scored three tries in Saturday's 53-0 victory over Fiji and has profited from Trimble's disappointing afternoon against the Springboks.
"I'm delighted to be involved. Obviously Argentina will be a different kettle of fish to Fiji," Gilroy said.
"I want to do well and take my opportunity. It's all happened pretty fast. I have to keep my feet on the ground and enjoy it."
Juan Martin Hernandez returns at full-back for Argentina after recovering from the thigh strain that forced him to miss the 39-22 defeat by France.
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