Maxi Rodriguez was on the scoresheet again as Newell's Old Boys recorded a 2-0 win at home to Argentinos Juniors.
Rodriguez netted for the fourth straight game, released down the right before unleashing a powerful finish into the bottom corner on 21 minutes.
The former Liverpool man missed a penalty seven minutes before half-time, but Pablo Perez doubled his side's lead in the second half.
Perez's cracking strike from just outside the area had too much power for Argentinos goalkeeper Paolo Migliore.
San Lorenzo stayed a point behind in second as they dealt with Gimnasia La Plata 3-0 at home.
Ignacio Piatti scored a brace for the victors, either side of Pablo Alvarado's 51st-minute goal.
Arsenal are two points further back after a 1-0 win over Godoy Cruz, who finished the encounter with nine men after two late red cards.
Emmanuel Gigliotti led Boca Juniors to a 2-0 win over Quilmes thanks to his brace and Gabriel Mercado's late winner saw River Plate past Lanus 1-0.
Racing Club remain winless and in bottom spot after a 3-0 loss to Belgrano, who had Cesar Pereyra score a brace.
All Boys and Rosario Central played out a 1-1 draw and Estudiantes and Velez Sarsfield were unable to be separated in a 0-0 result.
Atletico Rafaela battled past Olimpo 2-0 and Tigre edged Colon 1-0 in a game which saw four red cards shown.
