River Plate moved into the Copa Libertadores last 16, while Boca Juniors are yet to seal progression after being held on Wednesday.
Goals in either half from Javier Pinola and Ignacio Fernandez guided defending champions River to a 2-0 win over Palestino in Group A.
River opened the scoring just after the half-hour mark in Santiago, Pinola heading in a Fernandez set-piece at the back post.
Fernandez turned goalscorer in the 63rd minute, tapping in after Palestino goalkeeper Jose Ignacio Gonzalez smothered at his feet but was unable to hold onto the ball.
Julian Fernandez's 73rd-minute red card hurt the hosts' hopes of a comeback before River substitute Rafael Santos Borre was also sent off.
River will finish second to Internacional in Group A after the Brazilians continued their impressive campaign with a fourth win in five games.
Rodrigo Moledo's 80th-minute goal was enough for Internacional to overcome Alianza Lima 1-0 in Peru.
Runners-up last year, Boca came from behind to grab a 2-2 draw with Deportes Tolima in Ibague.
The Colombian hosts made a dream start, scoring twice in the opening 20 minutes through an Alex Castro strike and Marco Perez header.
But Boca were level before the break through Mauro Zarate and a Dario Benedetto penalty.
The result left Boca in second in Group G, a point behind Athletico Paranaense and three clear of Deportes Tolima and Jorge Wilstermann.
Athletico Paranaense are already through despite a 3-2 loss to Wilstermann on Wednesday.
Group D remains alive after top two Flamengo and Penarol suffered surprise defeats.
Flamengo top the group despite a 2-1 loss at LDU Quito, while Penarol were beaten 3-1 at San Jose.
With one game remaining, Flamengo and Penarol are on nine points and meet on the final matchday, while LDU Quito are on seven and host San Jose (four).
In Group H, Universidad Catolica played out a 1-1 draw with Rosario Central.