Lanus extended their lead at the top of the Clausura table to three points with a 1-0 win at Godoy Cruz.
Carlos Izquierdoz scored the only goal after 27 minutes and, with River Plate slipping up, it was enough to pad Lanus' cushion at the top.
River were beaten 1-0 at Newell's Old Boys, who leapfrogged them into second place, thanks to a 36th-minute strike from Ignacio Scocco.
The other three matches all ended 1-1.
Racing Club took the lead against Belgrano Cordoba after 12 minutes, but were pegged back by Jorge Velazquez five minutes after the break.
Two goals in a minute saw Velez Sarsfield and Estudiantes share the spoils, with Federico Insua putting Velez ahead in the 77th minute and Leandro Benitez replying immediately for the visitors.
The hosts had Fabian Cubero sent off late on.
Matias Martinez scored on the stroke of half-time to salvage a point for Argentinos Juniors at Boca Juniors, who had opened the scoring through Santiago Silva's 13th-minute penalty.
On Saturday, Quilmes missed the opportunity to go level with the Clausura leaders as they were held to a goalless draw by Independiente.
In the day's other game, an own goal from Ruben Ramirez 15 minutes from time gave San Lorenzo a 1-0 win at Colon Santa Fe.
San Lorenzo played nearly an hour with 10 men after Mauro Cetto was sent off in the 33rd minute.
Ten-man All Boys claimed their second victory of the Argentinian Clausura season on Monday night with a 2-1 home success against Atletico Rafaela.
Two goals in as many minutes towards the end of the first half, from Angel Vildozo and Ivan Borghello, put the hosts in the ascendancy before Fernando Sanchez's 70th-minute red card ensured a nervy ending.
Sanchez was sent off for a second bookable offence after a needless handball inside his penalty area and Juan Eluchans converted the resulting spot-kick, but Atletico could make no further inroads despite their man advantage.
The result lifted All Boys to ninth in the standings - two points and five positions better off than their visitors after six games.
Also on Monday night, Lisandro Lopez netted a last-gasp winner to spare Arsenal Sarandi's blushes in a 3-2 victory over San Martin San Juan.
First-half goals from Victor Cuesta and Julio Cesar Furch looked to have put the home team in the driving seat, but the visitors were back on level terms within six minutes of the restart thanks to Christian Alvarez's penalty and Humberto Osorio's equalizer.
However, Lisandro had the final word to lift his side to fifth place in the standings and deny the opposition what would have been only their fourth point of the campaign.
