Dario Gandin's last-gasp goal earned Independiente a 1-0 victory over San Martin from Tucuman to move to the top of the Apertura standings.
Independiente struggled to break down the recently-promoted side's defence until stoppage time when playmaker Daniel Montenegro found forward Gandin to score.
Gaston Fernandez scored twice as Estudiantes twice came from behind to draw 2-2 with Banfield, who finished the match with 10 men following the dismissal of Luio Barraza.
Marcelo Bustamante and Renato Civelli were on target for Banfield, but Fernandez twice equalised.
Banfield midfielder Civelli said: 'This is a very valuable point for us.
'Estudiantes are a very tough rival, especially at their home and we managed to clinch a point despite being a man down during the second half.'