Impossible, they'll have to meet in the semis.
I'm pretty sure Argentina are on our side of the draw and Czech are on the other side with Brazil. That's only off the top of my head though, I haven't checked it.
Argentina have to be one of the favourites after that performance today. However, from that side of the draw it will be Germany. They are always there, regardless of how strong they are. Last time it was supposed to be their worst ever team, yet they still made the final. This time at home, it will be no different. I expect them to be there. So I guess it will be Germany or Argentina from that side of the draw.
From the other side, Brazil have to be favourites, just because they are Brazil. I suppose Spain have to have a chance although they will get dumped out first time they play a top team IMO, just like they always do. Czech Republic will go far.
So assuming I have got the draw right, I think it will be:
Germany/Argentina vs Brazil/Czech Republic
I'm not going to cut that down to 2 just yet.