PUERTO LA CRUZ, Venezuela, July 5 - Argentina finished the group stages of the Copa America as the only team with a 100 percent record after Javier Mascherano's strike gave the tournament favourites a 1-0 win over Paraguay on Thursday.

But while Argentina eased into the last eight amid plaudits for their attacking football, arch-rivals Brazil were under fire for coach Dunga's allegedly unimaginative tactics.

Substitute Mascherano scored Argentina's winner, his first international goal, with a superbly-placed shot in the 79th minute of the Group C match in Barquisimeto.

The win guaranteed Argentina first place in the group and avoided a quarter-final against Mexico. Instead they will face Peru, theoretically easier opponents, on Sunday.

Paraguay finished second on six points and will be Mexico's opponents, also on Sunday.

Earlier, Colombia salvaged some pride by beating United States 1-0 to finish with three points while the U.S. went home pointless after losing all their games.

Both teams had been eliminated before they kicked off.

Jaime Castrillon headed a 15th minute winner for Colombia, while Hugo Rodallega missed a penalty and goalkeeper Robinson Zapata was sent off in the 86th minute after being booked twice for time-wasting.

TOUGH MARKING

Argentina, who made eight chances to their starting line-up, struggled to break down a tough-marking Paraguay side.

Carlos Tevez and Rodrigo Palacio both hit the woodwork early in the second before Mascherano ended their frustration shortly after coming on as a substitute.

"It's not usual for me to score, the important thing is we won and the team played well," the Liverpool midfielder told reporters.

"We won well, they defended with eight or nine and we tried all sorts of variations," Argentina coach Alfio Basile added.

"We deserved to win because we were superior."

The other quarter-finals will be on Saturday when Brazil face Chile and hosts Venezuela meet Uruguay.

Brazil go into their match under intense criticism after scoring only four goals -- all from striker Robinho including two controversial penalties -- in Group B, compared to Argentina's nine.

The Rio de Janeiro daily O Globo led the criticism following Wednesday's 1-0 win over Ecuador, describing it as "another dreadful performance".

Other newspapers joined in, pointing out that the team was over-dependent on Robinho.

The players, however, said results were more important.

"Football is about the result and getting three points. I prefer the result. The important thing is that we're winning," midfielder Anderson said.