(Saturday, 3 p.m. ET)
If you were planning the perfect progression through a tournament, you'd begin slowly, doing just enough to qualify without anxiety, slowly uncoiling toward top form in the semifinal and final. That is exactly what Colombia has done, strolling through at the top of Group A with seven points that should have been nine, and giving the impression of playing well within itself. So much energy was expended discussing the reasons for Argentina's poor showing in its second game that the quality of Colombia's display was rather overlooked. Carlos Sanchez was excellent at the back of midfield, stifling Lionel Messi, and but for barely credible misses from Adrian Ramos and Dayro Moreno and three squandered one-on-ones it would have won comfortably. It knew a win against Bolivia in its final game would be secure top-spot in the group, and it had it wrapped up within half an hour, the Porto forward Radamel Falcao scoring twice, one a penalty, in a 2-0 victory. The 4-1-4-1 shape has worked well, the two wide men, Moreno and Ramos, getting forward to offer Falcao support, with Fredy Guarin a busy, neat presence in the middle of midfield. Peru, meanwhile, although far better than in World Cup qualifying, when they finished bottom of the Conmebol group are essentially organized but limited, only the left winger Juan Vargas offering much in the way of creativity, although Paolo Guerrero has proved himself an effective leader of the line. Colombia's concern will be that two packed midfields cancel, but it should be strong enough to reach the semifinal.
(Saturday, 6:15 p.m. ET)
Argentina's penalty for finishing second in the group is severe; rather than a tie against Peru in Cordoba, it faces a platense derby in Santa Fe. The host finally turned up on Monday, in its third game. Admittedly, it was only against a weakened Costa Rica side, but still, there was at last a sense of cohesion about its 3-0 win. The introduction of Fernando Gago and Angel Di Maria for Ever Banega and Esteban Cambiasso in midfield gave the skewed triangle shape desirable in a 4-3-3, with Javier Mascherano sitting deep, Gago just advanced of him to the right, and Di Maria advanced of him to the left. The result was a more natural linkup to the front three. Lionel Messi began on the right, drifting more and more central as the game went on, with Gonzalo Higuain offering an aerial threat (even if his finishing was badly awry) and Sergio Aguero cutting in from the left. Suddenly there were short passing options everywhere, allowing Argentina to develop the rhythm it has at its best. The third goal, scored by Di Maria after yet another dart and run form Messi, followed a mesmerizing spell of passing lasting well over a minute. The question is whether Argentina can hit those heights again against Uruguay, who will be an awkward opponent. It has been the best pressing side in the tournament. Following a sloppy beginning in drawing 1-1 with a Peru, Uruguay has struggled to find much fluency, troubled seemingly by a defensive line that was alternately too high and too deep, and by the poor form of the forward Edinson Cavani. The game against Mexico was no thriller, but the pressing was back and, with Cavani injured, the switch to a 4-4-1-1 formation, with Diego Forlan dropping off Luis Suarez, gave it much greater solidity.
(Sunday, 3 p.m. ET)
At 1-1 at halftime in Brazil's final group game, against Ecuador, Mano Menezes could have instructed his side to shut up shop and play for a draw that would have secured a quarterfinal against Venezuela. Instead his side kept attacking, won 4-2, and so will play Paraguay, the side that was within a minute of beating it in the group stage. Pato, scorer of two of the goals against Ecuador, spoke of the dawn of "a new Copa" for Brazil, but for all the renewed fluency in attack, Brazil looked distinctly wobbly at the back. Lucio has been a fine defender for several years, but his diminishing pace is a concern, and was at least partly responsible for how vulnerable Dani Alves looked against Paraguay when Marcelo Estigarribia dominated him. The Newell's Old Boys winger's reward for that performance will probably be to face the more defensively-sound Maicon in the last eight. Paraguay itself has played rather better than a record of three draws might suggest. It had the better of a goalless draw against Ecuador, led Brazil until the last minute, and was 3-1 up against Venezuela with four minutes to go. For a team with a reputation for doughtiness, that is a barely explicable failing, and it may be that Nestor Ortigoza needs some assistance at the back of the midfield. The danger, of course, is that in supplying it, Gerard Martino robs his team of the fluency that has been such a refreshing surprise in this tournament.
(Sunday, 6:15 p.m. ET)
The parrillas on Avenida Sarmiento in Mendoza were awash with red on Tuesday, and not that much quieter on Wednesday. Chile lies only 130 miles west across the Andes, and its fans have come in huge numbers, with reports of tailbacks of over six hours at the border. The result is that Chile has effectively had home advantage in the group stage, and it will do so again in its quarterfinal only a couple of hours north in San Juan, where it played its first match. Although its third match, a 1-0 win over Peru, was pretty dire, a last-minute own goal won it for Chile after 90 minutes in which neither side had managed a shot on target at the right end. For the first week of the tournament, though, Chile, with its adventurous 3-3-1-3 shape, had been the most watchable side. Claudio Borghi's team may not press with quite the same ferocity as predecessor Marcelo Bielsa's did, but it still plays a distinctive style of soccer, and has the cohesion of a team not much changed since the World Cup. Alexis Sanchez, linking well with Mauricio Isla on the right, has impressed, while Jorge Valdivia was superb after coming off the bench in a playmaking role against Uruguay. Although the Chilean fans in Mendoza clearly preferred Venezuela as a quarterfinal opponent, the vinotintos are an emerging force. Solid at the back (if vulnerable from set plays), with Tomas Rincon and Franklin Lucena protecting the back four from deep in the midfield, it has imagination and quality going forward. Cesar Gonzalez is an industrious winger; Jose Rondon, although raw, is a fine finisher and both Juan Arango and Giancarlo Maldonado have an imagination to match their quick feet. Chile should win, but it might not be as easy as the chilenos in the parrillas seem to think.
Jonathan Wilson is the author of Inverting the Pyramid; Behind the Curtain; Sunderland: A Club Transformed; and The Anatomy of England. Editor of The Blizzard.