Four matches, four upsets.

Argentina, Chile, and Colombia? Hasta luego.

Brazil? Ate breve.

Uruguay is the only nation heading into the semifinals of the Copa America with a world class roster. Venezuela, Paraguay, and Peru shocked their opponents, and now the Copa America tournament has a major shortage of star power.

For Brazil and host-nation Argentina, there are a lot of questions to be answered for their respective early exits, and it's interesting to ponder which team suffered more humiliation in South America's most prestigious tournament.

The only acceptable result for Argentina, by the fans and press, was winning the title. Argentina hasn't won a World Cup or Copa America trophy since Mexico City in 1986, behind the legendary performance of Diego Maradona. With a roster packed with excellent defensive players, and a star-studded collection of forwards, Argentina had high hopes going into the tournament on their home soil.

But certain weaknesses were exposed. Unlike in years' past, Argentina were without the services of an elite goalkeeper. Sergio Romero did a solid job in the net, but he is not up to the standards of past goalkeeper stars like Sergio Goycochea, Pablo Cavallero, and Roberto Abbondanzieri.

Another spot that has been somewhat of a concern, dating back to when Maradona retired, has been attacking midfielder. Javier Pastore appears to be the best player at the position, but he went into the tournament with limited experience, and head coach Sergio Batista didn't appear to use him right, even bringing him off the bench, when he probably deserved to start.

In fact, a great deal of the blame could fall on the shoulders of Batista. After replacing Maradona, the new coach didn't seem to understand his team's strengths, or how to develop chemistry.

Argentina sputtered against hapless Bolivia, and managed only a tie against Colombia. To advance to the knockout rounds, they defeated a weak Costa Rica team that lacked their best talent.

Against Uruguay, Argentina appeared sharp on offense, but the defense was terrorized by forward Diego Forlan's freekicks from near the half line and into the penalty box.

However, when Diego Perez received his second card in the 38th minute, Argentina had the man advantage and had the opportunity to pounce on Uruguay until the 87th minute when Javier Mascherano received a questionable second yellow card. Argentina's inability to capitalize against 10 players for nearly 50 minutes proved that the South American giants lacked the great passing and attack style to be mentioned with the likes of European powers Spain, Germany, and the Netherlands.

Argentina did receive quality play from Barcelona star Lionel Messi. The overly criticized forward did not score in the tournament, but was a great facilitator against both Costa Rica and Uruguay. Meanwhile, forward teammate Sergio Aguero struggled for most of the match, and normally reliable Angel Di Maria was rather ineffective against Uruguay.

To Argentina's credit, they still manage a goal, were impressive in the penalty shootout, and appeared to be the stronger team against a talented Uruguay squad. The 2010 World Cup semifinalists played with great poise, and did a fine job of executing on their limited opportunities.

While Argentina had a few bright spots in their quarterfinals loss, the same probably cannot be said for Brazil.

Head coach Mano Menezes took a curious lineup into the tournament, and Brazil seemed to lack the creative flare that they've been known for in the past.

Brazil had two draws, and managed only one win over hapless Ecuador. Even in that victory over Ecuador, Brazil conceded two goals, and were tied with two-thirds of the match complete.

Against Paraguay in the quarterfinals, Brazil dominated most of the match, but was stymied by a tough defense. Brazil also showed that they no longer have a superstar forward, as Alexandre Pato, Robinho, and 19-year-old Neymar proved that they are not up to the former standard of Brazil strikers.

In particular, Neymar may have proved that he's more hype than anything. The young forward scored two goals in the tournament, but both were against Ecuador, who were not expected to advance.

With zero goals after 120 minutes, Brazil's penalty shootout was nothing short of pathetic. Not only did they not convert one shot, their shots were dreadful.

Menezes's job security is probably very shaky at the moment. Brazil remains strong at defense and at goalkeeper, but the midfield and forward positions proved that they lack high-quality attackers and playmaking skills. Menezes failed to find the right unit to put more pressure on opponents.

For Brazil and Argentina, it's time to pick up the pieces. Brazil will host the Confederations Cup in 2013, and then the World Cup in 2014.

With the world watching South America, the two most prominent nations on the continent are expected to rise to the occasion or risk even more criticism.