The diminutive four-time player of the year has finally sparked for his country, hitting four of their six goals as Argentina qualified top of Group F.
But Argentina needed Messi's late winner to overcome Iran 1-0 and they also shipped two goals before beating Nigeria 3-2, lowering expectations of a third world title.
They will face their toughest opponents yet in Switzerland, who put seven goals past group opponents Ecuador, France and Honduras, including three from Xherdan Shaqiri.
"There is nothing more beautiful than to be world champion, to achieve that with my country."
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In Argentina's favour is that more than 100,000 of their fans are expected to flood Sao Paulo ahead of Tuesday's game, including many inside Corinthians Arena.
But they will have to cope with the loss of Manchester City forward Sergio Aguero, who is out with a muscle injury after going off in the first half against Nigeria.
Both Messi and coach Alejandro Sabella acknowledge that Argentina are a work in progress but they will now hope to raise the heat on their slow-burning campaign.
Former Bayern Munich coach Ottmar Hitzfeld will relish the clash against one of the pre-tournament favourites in what he says will be his last hurrah before retirement.
Despite their 5-2 hammering by France, Switzerland have twice bettered Latin American opposition already after their 2-1 and 3-0 wins over Ecuador and Honduras respectively.
Their attack will be spearheaded by one of the revelations of the tournament, 22-year-old Shaqiri, who hit all three goals against Honduras to secure Switzerland's qualification.