This will probably be Oscar Washington Tabárez's final Copa América. He is 64 and five years into his second spell as coach of his homeland. He has spoken eloquently of the need for continuity and made the point during the World Cup that the impressive showing of Paraguay and Chile, as well as his Uruguay, stemmed from the fact that each of their coaches had been in charge since at least the previous Copa América.

After the success he has had, leading Uruguay to a first World Cup semi-final in four decades, embarking on a second four-year cycle is a clear risk and, in their two games in the tournament so far, Tabárez's side have yet to win. A victory against a weakened Mexico in their final group game will carry them to the quarter-final, but they are some way short of the heights they reached in South Africa, when Diego Forlán was named player of the tournament.

Forlán himself has been lively, much sharper than he looked in a disappointing season for Atlético Madrid, while Luis Suárez has been superb, scoring the equaliser against Peru in Uruguay's first game and laying on Alvaro Perreira's goal against Chile on Friday. Edinson Cavani, perhaps, has not lived up to the standards he set for Napoli last season, but, for once, Uruguay's problem is at the other end of the pitch.

Uruguayan football has always been noted for its garra– a word that translates literally as "claw", but which, in a football context, has come to mean a combination of hardness, resolve and streetwiseness.

That has led in the past to excessive physicality, but Tabárez's interpretation is rather more nuanced. On the wall of his house in Montevideo hangs a plaque bearing the motto: "One must toughen oneself without ever losing tenderness." It is a line attributed to Che Guevara and marks El Maestro, as Tabárez is known, in the grand tradition of left-leaning South American footballing intellectuals. It also seems to summarise his footballing philosophy: he prioritises defensive rigour while still encouraging his teams to play with a certain swagger.

With his neatly parted grey hair, navy or grey jacket and striped tie, he resembles the precinct chief in a 70s cop show, but he is one of football's great thinkers, somebody who regards the game as a part of culture to be discussed and debated. "You mustn't demonise the word defence," he has said. "When a coach wants to be popular, they say they are an attacking coach. When a coach says he is defensive, it is assumed something is lacking. But we have good attackers and we insist on the intelligence of players knowing when to attack and when to defend. This is a virtue. It is not a crime to be strong in defence."

The problem is that this Uruguay do not look strong in defence. Paolo Guerrero's goal for Peru was the result of Mauricio Victorino and Diego Lugano playing a ridiculously high offside line, and that seemed to create doubt in that game as to the positioning of the back four. It returned against Chile after the introduction of Jorge Valdivia. Tabárez seemed to have won the tactical battle by replacing the injured Cavani with Alvaro González and switching from 4-3-3 to 4-4-2, which had the effect of freeing Suárez from the left flank to float more centrally and of liberating Perreira to attack on the left, circumventing Chile's narrow midfield. It was the two who combined for the goal. But when Valdivia came on, suddenly Uruguay looked shaky again, the gap between back four and midfield a particular worry.

As the grandees have struggled, Chile have probably been the most impressive side at the Copa América so far. Marcelo Bielsa may have gone, and with it his radical pressing, but under the Argentinian Claudio Borghi the attacking approach remains. Suárez commented that the Uruguay-Chile game saw "two teams who wanted to win", which has certainly not been the case in every game so far in this tournament, but more than that it showcased two teams with a clear idea of how they might go about doing so.

Chile are playing well and, while Uruguay have defensive issues, they can at least console themselves with the thought that they have started the tournament far more impressively than either Argentina or Brazil. It may not suit the marketing gurus, but if either can go all the way and prevent a third straight Argentina-Brazil final, it must be a positive for South American football as a whole.