I expected that it will be more difficult game for Netherlands, they didn't impressed me in group stage and I liked how USA looked there. But today Netherlands remind me team that they had in 2010-2014.
Argentina - Australia. Unbeleavable, but true - Messi scored his 1st play-off round goal in his 5th World Cup. Argentina controlled game until Australia scored goal out of nowhere and it made last 15 minutes very interesting. That moment when Australian defender went through maybe 4 Argentina players and almost scored goal was amazing.
Argentina - Netherlands in 1/4 final, this is where big games begins

I will add Mexico and Serbia too.
Germany, Uruguay, Mexico were doing everything but because of the result from other matches, they had could not qualify even after winning their last match with dominance.
Well, before tournament Mexico reaching next round didn't looked like obvious scenario, they're not that much better team than Poland. And Serbia, they have some good players, but they never had good perfromances at big tournaments. Personally, in FIFA predictor I marked both these teams on 3rd place before tournamnet.
Argentina vs Netherlands will be really intresting and i think that match will go in to extra time,i really dont see anyone winning in the first 90 minutes both teams are at same level as far as i seen at this world cup. Serbia had big expectations but ended up last in the group with some big players in their squad.