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A hard-fought 1-0 win at Newell's Old Boys saw Colon move level on points with Estudiantes, who were held to a scoreless draw at home to River Plate.
Estudiantes remain top on 25 points with their +6 goal difference, which is two goals better than Colon (25 points, +4).
Gimnasia La Plata sit third a point back but level with River Plate in a congested top half of the table.
At Newell's, Lucas Alario headed in the game's only goal on 76 minutes at the Estadio Marcelo Alberto Bielsa.
Marcelo Melli's well-weighted cross from the right found Alario's run and the striker found the bottom corner.
The goal came just two minutes after Newell's midfielder Lucas Bernardi had been sent off having picked up two quick yellow cards.
Newell's finished the encounter with nine men as Raul Villalba was sent off, while Leando Castillo saw red for the visitors.
Gimnasia La Plata stayed in touch with the top two with their fourth straight league win, a 1-0 victory at Racing Club on Thursday.
Fifth-placed Rosario Central continued their good form with an entertaining 3-2 win at Atletico Rafaela.
Franco Niell and Paulo Ferrari scored in 11 second-half minutes, finally capitalising against an Atletico side who were reduced to 10 men after half an hour and finished with nine.
Bottom side Arsenal were held to a 1-1 draw at All Boys and Argentinos Juniors' struggles continued with a 3-0 loss at Olimpo.
Quilmes struck twice in the opening nine minutes on their way to a 3-1 win at Velez Sarsfield and Godoy Cruz edged Belgrano 2-1.
The clash between Boca Juniors and San Lorenzo finished in a scoreless draw.