River Plate moved level on points with Primera Division leaders Gimnasia La Plata thanks to a 3-2 victory over Racing Club.
Argentina's league leaders Gimnasia were held to a scoreless draw at home by Lanus on Sunday and River Plate took advantage, holding off Racing to move level at the top of the table with 31 points.
But River Plate had a slice of fortune against Racing with Leandro Chichizola saving a penalty in second-half stoppage time, which would have secured a draw for the visitors.
While River Plate remain second on goal difference, they increased the pressure on Gimnasia, while third-placed Estudiantes also made the most of the leaders' slip up at home with a 2-0 victory at Colon.
River Plate hit the front in the 25th minute at the Estadio Monumental Antonio Vespucio Liberti after Racing failed to clear their defence on a number of occasions and then saw Esteban Saveljich barge into the home side's Daniel Villalva to give away a penalty.
Skipper Fernando Cavenaghi stepped up and converted the spot kick but Racing equalised in the 38th minute when Diego Villar headed Rodrigo de Paul's free-kick into the net.
Despite that, River Plate led at half-time as Villalva's centring pass was struck into the roof of the net from the edge of the area by Carlos Carbonero two minutes before the break.
Just nine minutes into the second half and the hosts looked to be cruising when Cavenaghi claimed his second goal, flicking the ball home from close range from Carbonero's cross.
But Racing responded again with Gabriel Hauche's fine finish in the 73rd minute setting up a nervous finish for the home side.
The hosts hit the post soon after, although Racing had the best chance to score in the latter stages.
After River Plate defender Jonathan Maidana fouled Valentin Viola just outside the box and was sent off, Ariel Rojas used his hand to block Racing's free-kick and the referee pointed to the spot.
The visitors' goalkeeper Sebastian Saja took responsibility but could not beat Chichizola from 11 metres.
In Colon on Saturday, Franco Jara and Guido Carrillo scored either side of half-time to give Estudiantes victory over the home side, who had Gerardo Alcoba sent off six minutes into the second half.
The win saw Estudiantes leapfrog Godoy Cruz in the table, with the latter giving up a lead in their 1-1 draw with Velez Sarsfield.
Boca Juniors claimed their third win in a row thanks to a brace from Juan Manuel Martinez, prevailing 3-1 over bottom club All Boys, while Emilio Zelaya's 88th-minute strike saw Arsenal triumph 3-2 over Newell's Old Boys.
In other results, Tigre defeated Belgrano 2-1 on Monday, while San Lorenzo trumped Atletico Rafaela 2-0 and Rosario Central's hosting of Olimpo ended 0-0.