The favorites have not had it easy so far.
Germany had to endure extra time after going 0-0 in normal time with Algeria.
Brazil won on penalties after a Chile shot deflected off the crossbar in extra time.
The Netherlands were about 5 minutes away from elimination before drawing level with Mexico. They won with a somewhat dubious 95th minute penalty score.
This made France's 2-0 win - which was a tense 0-0 draw until almost the 80th minute - seem like a stroll in the park.
No big favorite has been knocked out of the round of 16, but they all have had their scares.
Argentina will want to follow Colombia, who got their lead in the first half and never looked back. But to do so, they will have to contend against a hungry Swiss team led by their star, Xherdan Shaqiri.
The Bayern Munich man scored a hat trick in the last game of the group stage with the help of striker Josip Drmic. That combination will be the main problem for an Argentina team lacking true stars in defense. Barcelona's Javier Mascherano will have a big role to play yet again in the middle of the park.
Meanwhile, Diego Benaglio is a talented keeper and will have to do his best to keep Lionel Messi quiet. Argentina will hope Gonzalo Higuain will rediscover his form. The Napoli striker has not been up to his best this World Cup but remains an important figure,
This is doubly so because Sergio Aguero picked up an injury and may be out for the rest of the cup. "Kun" looked off and unfit in his previous games, but with him out, it only increases the pressure on Higuain to become the secondary scoring option.
His replacement, Ezequiel Lavezzi, is not nearly as clinical, but does offer pace and width. Crucially, he could be tasked with a little more defensive responsibility than Aguero.
Messi's supporting cast will have to deliver more if Argentina aspires to win the cup. Angel Di Maria showed sparks lately and if he reaches his highest level, look out.
Should Argentina continue to improve as they affirm they are confident they can do, they should make short work of a talented but unfancied Swiss side.
Otherwise, one of the favorites may be in for a long 120 minutes yet again.
Argentina (4-3-3): Romero; Zabaleta, Garay, Fede Fernández, Rojo; Gago, Mascherano, Di María; Messi, Higuaín, Lavezzi
Switzerland (4-2-3-1): Benaglio; Lichtsteiner, Djourou, Schär, Rodríguez; Behrami, Inler; Xhaka, Shaqiri, Mehmedi; Drmic