River Plate saw their Copa Libertadores dream come to a painful end following a 4-2 defeat to Nacional.
Colombian forward Radamel Falcao Garcia put the Argentinian side ahead with a penalty but Fabio Escobar equalised before the break for the Paraguayans, also from the spot.
River were reduced to 10-men in the second period following Diego Buonanotte's red card and substitute Jorge Nunez scored twice for the hosts before Carlos Peralta made it 4-1 to a team that had already been eliminated from the competition.
Marcelo Gallardo netted a consolation goal eight minutes from the end with a precise free-kick.
"This is an unexpected blow for us. It's very hard to play away with one man less," said River defender Nicolas Sanchez.
The result means Uruguayan giants Nacional and Peru's San Martin advance to the last 16 from Group Three.
Ecuadorians Deportivo Cuenca kept their hopes of progressing to the knockout stage alive after they defeated Argentinian powerhouses Boca Juniors 1-0.
Edison Preciado scored the only goal of the game in the 76th minute with a pinpoint shot from the edge of the area.
"We could not seal qualification but the result is not the end of the world. We created chances to score. Anyway, we will qualify at home," said Boca Juniors coach Carlos Ischia.
Boca still top Group Two with 12 points, while Deportivo Cuenca are level with Venezuelans Deportivo Tachira in second on nine points.
Cuenca will travel to Paraguay to take on already-eliminated Guarani while Tachira go to La Bombonera stadium to face Boca Juniors in the final round of matches.