The group stage is over, and we're now at the business end of the Copa America. ESPN FC's Miguel Delaney, on the ground in Chile for the tournament, runs the rule across the four quarterfinals.

Chile vs. Uruguay

All the momentum is with Chile, but all the history is with Uruguay.

The hosts have looked to be far and away the best team in this tournament so far, scoring twice as many goals as everybody else, but Uruguay have by far the best record in spoiling such house parties. On the past three occasions that the latter have met the home team -- Argentina 2011, Venezuela 2007 and Paraguay 1999 -- they have eliminated them.

That's all the more relevant here because it reflects just how good the Uruguayans are at digging in and disrupting more exciting and excitable sides. Oscar Tabarez's current side are experts at that, and abnormally difficult to beat.

Chile, however, have looked abnormally difficult to stop. Their performances so far have almost touched what you would imagine manager Jorge Sampaoli sees as his peak football: brilliantly cohesive quick interchanges in tight spaces, before electrifying long bursts.

The Arturo Vidal scandal doesn't seem to have punctured that cohesion. By contrast, it seems to have strengthened it. Right through the squad, Chile are speaking about how they know they must not waste an historic opportunity to win a first title.

It would not be the first time that Uruguay have disrupted such momentum, though, and they seem to relish it. Also, while Chile may be a far superior team in open play, Tabarez's side are exceptional at set pieces, which is exactly what the hosts are most susceptible against.

These contrasts could well make this the most engaging tie of the round. One nation holds its breath, the other still holds the trophy.

Peru vs. Bolivia

It's by far the least glamorous tie of the round, but it's for exactly that reason that this match offers something the others don't. It presents a genuinely historic opportunity for both sides, creating a rare mutual excitement. Peru could reach their second successive semifinal, but just their third in the past 30 years, while Bolivia could reach only their second semifinal in 50 years.

They're also very different types of overachieving outsiders. Peru have been typically steady, keeping things tight. Bolivia have oscillated wildly, going from the exhilarating 3-2 win over Ecuador to the 5-0 defeat to Chile, although the latter has to be put in the context of the fact they already knew they were qualified from the opening round for the first time since 1997.

Part of that is because their manager, Mauricio Soria, has said he specifically wants to replicate what Marcelo Bielsa did with Chile, and give Bolivia a new and adventurous football identity. Reaching the semifinals would be a significant milestone and statement in that regard, but Peru will be thinking along much the same lines. For both countries, this is epic. That should underscore everything about this fixture.

Argentina vs. Colombia

A pairing that will no doubt have brought sighs from both camps, but should bring out eager anticipation in everyone else. If these two sides couldn't possibly have got worse opponents to play given where they finish in the group, it has created by far the best pairing of the round.

The one caveat -- and potential wild-card factor -- is that neither side is on their best form. Both managers have yet to work out their best formation, and there is an argument that they have actually limited the scope of so many sensationally good attackers.

Argentina obviously have much more talent, not least in Leo Messi, but that is somehow offset by the fact Colombia coach Jose Pekerman has the more obvious solution to his issue. As so many games in this Copa have illustrated, Colombia -- and James Rodriguez -- radically improve once the ailing Radamel Falcao is taken off. That is going to require a big decision from Pekerman ahead of a big game, although his selection is obviously complicated by the absences of the abrasive Carlos Sanchez through suspension and Enner Valencia through injury.

Finding the right balance will be difficult, but Gerardo Martino has a similar problem with the players he can actually field. The Argentina manager, like many of his predecessors, has yet to work out an approach that maintains a certain security but also releases the creativity of so many brilliant attackers. The Argentines still seem like a side waiting on one of those players to produce a moment of brilliance, rather than that being the natural consequence of their play.

That may just be enough in this game, especially when you have Messi waiting to explode, but it is likely to be an anxious night.

Brazil vs. Paraguay

The crux of this quarterfinal is the question of which Brazil will show up. Because, while we can be fairly sure of the awkward challenge that Paraguay pose, there is even more uncertainty about Dunga's side than before the Copa America began.

Will we see the side from the start of the Venezuela victory that finally looked so balanced, or the one from the end of that match that looked so fragile? Will we see the side seemingly released by the absence of Neymar, or one that suddenly realises again how much better he is than everyone else on the team, buckling as they did in the 7-1 humiliation to Germany.

The bottom line is that Brazil are more beatable than they've ever been. That will make for a tense affair, but the wonder is whether it will be telling.

Miguel Delaney covers the Premier League and Champions League for ESPN FC. Twitter: @MiguelDelaney.