Walter Erviti scored the only goal to ensure Boca Juniors finished the weekend second in the Clausura table with a 1-0 win at San Martin San Juan.
Erviti struck 20 minutes from the end, leaving Boca a point behind leaders Tigre.
Newell's Old Boys and Arsenal Sarandi also claimed 1-0 wins to maintain their respective good starts to the Clausura campaign.
Mauricio Sperdutti struck after 23 minutes for Newell's Old Boys as they beat Atletico Rafaela, while Arsenal Sarandi saw off Banfield thanks to a goal from Jorge Ortiz in the eighth minute.
Ten-man Colon Santa Fe came from a goal down to claim a point in a 1-1 draw at San Lorenzo.
Colon had Esteban Fuertes sent off in the 32nd minute and they fell behind on the stroke of half-time thanks to Enzo Kalinski, but they levelled through Ariel Garce in the 68th minute.