Osvaldo Miranda scored the only goal of the game just before the half-hour mark to give the home side their fourth win from the opening six games and take them two points clear of second-placed Newell's Old Boys.
All Boys, who had Roberto Battion sent-off after 62 minutes, slip to 15th.
Estudiantes missed the chance to leapfrog Newell's following a 1-1 draw at home to Belgrano Cordoba.
Guido Carrillo gave the hosts a 44th-minute lead but Ezequiel Maggiolo levelled with 15 minutes to go.
Gimnasia La Plata drop to fourth after going down 2-1 at Atletico Rafaela.
Rodrigo Depetris and Andres Rodales scored for Atletico with Facundo Pereyra's last-minute strike nothing more than a consolation.
Jonathan Ramis grabbed an 84th-minute winner as Godoy Cruz beat Colon Santa Fe 1-0 while Racing Club and Lanus drew 1-1 in a stormy encounter.
A Carlos Araujo own goal three minutes from time appeared to have given Racing their first win of the season, especially as the visitors were down to 10 men following the 83rd-minute dismissal of Nicolas Pasquini.
But after both Racing's Fernando Ortiz and Lanus' Paolo Goltz had also seen red, Lanus equalised when Maximiliano Velazquez drove home left-footed.