Both Boca Juniors and River Plate made up for disappointing starts, beating Lanus and Chacarita Juniors respectively.
Boca Juniors visited Lanus and went ahead through Julio Caceres in the 17th minute. Agustin Pelletieri levelled five minutes later but a header from former Villarreal player Martin Palermo secured Boca's victory in minute 70.
River Plate's win over Chacarita Juniors was hard-fought. The Buenos Aires outfit scored the opening goal through Diego Buonanotte in the fifth minute, but had that goal cancelled out by Gustavo Alustiza in the 22nd.
Cabral then made it 2-1 in the 32nd minute but Alustiza again equalised just before the break, for Facundo Parra to make it 2-3 eight minutes after the interval.
River had enough energy left however. Daniel Villalba levelled eight minutes after the hour and the 35-year-old veteran Ariel Ortega made it 4-3 with two minutes to go at the Monumental Stadium.