Breaking down the last 16 in the Copa Libertadores

	In his first season back in Argentina, Juan Román Riquelme will try to guide Boca to its first Copa Libertadores title since 2003. AP
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Not so long ago, Argentine clubs owned the Copa Libertadores. Since the competition's inception in 1960, seven different Argentine teams have hoisted the trophy 20 times, far more than clubs from any other nation -- including Brazil.

Independiente is the Libertadores' all-time king, with a record seven titles. But since 1994, the only other Argentine club outside of five-time champion Boca Juniors to lifted the trophy was River Plate in '96.

Since then, Brazilian clubs have dominated, and it seems as if the trend will continue this year: Five out of the six Brazilian clubs advanced to the final 16 of the competition, compared to only two of the five Argentine clubs.

To make matters worse, the two remaining Argentine clubs (Boca Juniors and Vélez Sarsfield) will do battle in in what is expected to be the most fascinating encounter in the round of 16, which kicks off Wednesday night. The other mouth-watering matchup is the all-Brazilian showdown between past winners São Paulo and Grêmio of Porto Alegre.

Here's a look at all eight matchups, with my picks and a best-of-five-stars rating for how good the action should be.

Santos (1) vs. Caracas (16)

First meets last, it's as easy as that. This promises to be the most one-sided match of the round, considering that Santos has won all eight of its Libertadores matches by a combined score of 18-1. Caracas, on the other hand, only scraped into the last 16, but is motivated by the fact that it ousted Argentine powerhouse River Plate to get there. Still, another upset is highly unlikely.

Rating: Three stars
The pick: Santos

Colo-Colo (8) vs. Club América (9)

This is a potential classic between two giants that play a similar style. Both clubs encountered enormous difficulties before ensuring their final passage to the last 16, but both seem capable enough to reach the decisive stages of the competition, particularly because of their overall depth. But the similarities don't end there. Much of their success depends on the form of their top scorers: América's Salvador Cabañas and Colo-Colo's Humberto Suazo. The series is likely to be decided by one of these names.

Rating: Four stars
The pick: Colo-Colo

Flamengo (2) vs. Defensor Sporting (15)

Brazil's most popular club must have been relieved by the opportunity to face the low-profile Uruguayans from the Parque Rodó. The Rubro-Negro has returned to the last 16 of the competition after 14 years, and has everything in its favor to reach the final eight, especially if it makes the most of the Maracanã's intimidating atmosphere. But in order for this to happen, Flamengo can't underestimate its less glamorous opponent. Defensor has come to life in recent continental competitions, and although it may lack quality, it makes up for it with a never-say-die attitude.

Rating: Three stars
The pick: Flamengo