Estudiantes open up five-point lead
Alex Sabella's side, without injured captain Juan Sebastian Veron, scored just before the half hour when Gaston Fernandez brilliantly rounded goalkeeper Damian Albil and defender Fernando Meza to tap home the winner.
Estudiantes, notching their third win in eight days, have 22 points after nine matches. Velez Sarsfield, beaten 2-0 at Newell's Old Boys on Saturday, and Arsenal, who beat bottom team Quilmes 1-0, have 17 points.
River Plate, playing at Banfield in Sunday's last match, could go joint second with a victory.
There were goals galore on Saturday with 20 in four matches, notably fifth-placed Godoy Cruz's crushing 4-1 home win over hapless Independiente, who are one point off the bottom.
It was poor preparation for Independiente, still under caretaker coaches Elbio Pavoni and Pancho Sa, for the clash with arch-rivals Racing Club in the Avellaneda derby, second only to Boca Juniors v River Plate in "clasico" hierarchy, next weekend.
Racing continued their improvement with a 3-0 home win over Huracan, their third match unbeaten.