With the group stage over, we now know the QF setup:
Chile vs. Uruguay
Bolivia vs. Peru
Argentina vs. Colombia
Brazil vs. Paraguay
Chile vs. Uruguay and Argentina vs. Colombia are pretty scintillating matchups. Bolivia and Peru pits the two underdogs against each other and Brazil should be favored over Paraguay. As teams have now had 3 meaningful games and more time to train together, hopefully we will see some better aesthetic soccer going forward. This tourney has been notable for the compactness of most teams (outside of the ABC - Argentina, Brazil, Chile and to a lesser extent Colombia). I really hope the refs clamp down on strategic fouls and let these games breathe a bit more. Also, Neymar was suspended 4 games for his antics at the end of the Colombia match, so he is out for the rest of the tournament.
Chile put in the best performance of the tournament so far, shellacking Bolivia 5-0 to win Group A. I expect them to press Uruguay's backline, create turnovers, and have their creative attackers create lots of chances. Finishing will be key for them. By virtue of finishing 3rd in Group B, Uruguay draws the host. Uruguay has played very compact and physically so far. Cavani has not been great and Godin has been the best player. Alvaro Pereira will be out for the Chile match, which doesn't help. The team looks best on set pieces and attacking early crosses. With Suarez, this team would be a considerable threat but without him, I think Chile takes this in a not so close game.
I'll be honest and say I haven't watched much of Bolivia. But, I have seen Peru against Brazil and Colombia. This team is very resilient and sneaky good. They don't have any allstars, but they are solid at the back and can frustrate the opposition. Although Neymar's pass undid them late against Brazil, they played well in that game and announced their presence. Against Colombia, they shut down James and really frustrated the Colombia attack (which admittedly hasn't been great yet). They will likely have to bring the game to Bolivia in this match, and I expect that they will be able to get at least one past Bolivia and progress.
Argentina vs. Colombia has a lot of potential to be a great match. Argentina haven't shown their true talent level yet, but there is something to be said for not losing a match and getting results. Pastore has really started to play better, Argentina has gotten their bench players some minutes (Higuain, Demichelis), and the team still has that Messi fella. I still feel like Lavezzi should replace Di Maria in the lineup because he can provide the same width Di Maria does, but he can also make more incisive runs than Di Maria who is more of a creator than finisher. Tevez could also be included, but he plays more centrally. All 3 have good defensive effort though, which is quite a luxury. Colombia was frustrated in their match against Peru, but again, just getting to this point is important. James may have more room to operate in this game since Argentina will have to attack. Colombia can try to attack on the break, especially thru Cuadrado (who hasn't been utilized nearly enough yet IMO), but if Argentina scores early and opens them up, it could be a long day for the Cafeteros. Carlos Bacca and Carlos Sanchez are both out for this match and with Falcao's form pretty shitty right now, Colombia has a tough test ahead. James will need to have some moments of brilliance to dent Argentina. Nevertheless, they are still a good squad and should be competitive.
Brazil looked much better in their match against an underrated Venezuela side than in their match against Colombia. Alves and Willian were excellent going forward and the Brazilians were combining very well up front. Even Robinho looked pretty good. Coutinho still doesn't look comfortable, but he has so much quality, it's only matter of when, not if. David Luiz didn't start and the CBs (Silva and Miranda) looked just fine. This allowed Fernandinho to play in his natural position and the pieces looked to fit much better. I will be very interested to see if Luiz starts this match. Paraguay is a stingy defensive team that is very representative of CONMEBOL sides. They defend in numbers and compactly, and look to pip a goal and defend. Richard Ortiz is out for the Brazil match. I expect the Paraguayans to make it difficult for Brazil to find space, but since they can't really threaten Brazil going forward, Brazil should advance.