The home side took an early lead through Jorge Curbelo and doubled their lead through Mauro Obolo 11 minutes into the second half.
Although Rodrigo Gomez pulled a goal back for Argentinos Juniors in the 65th minute from the penalty spot, Obolo got his second of the game seven minutes later and a bad night for the visitors was capped when substitute Leandro Barrera was dismissed just 10 minutes after coming on as a 75th-minute substitute.
Julio Cesar Furch's last minute penalty salvaged a 1-1 draw for Arsenal Sarandi against Estudiantes in a game of three dismissals.
The home side faced an uphill task following the early dismissal of Mariano Echeverria and slipped behind to Duvan Zapata's 32nd-minute goal.
However, the visitors evened the numbers up when Jonathan Silva was sent-off five minutes before half-time.
And there was a lively finish to the contest, with Furch blasting in the equaliser from the penalty spot - and Estudiantes' Leonardo Jara picking up a red card.