Newell's Old Boys' Apertura title hopes suffered a blow as they could only manage a 2-2 draw at Union Santa Fe.
They fell two goals behind in the first half thanks to strikes from Diego Jara's 23rd minute strike and Andres Franzoia's goal after 34 minutes.
Martin Tonso, on as a half time substitute, scored within a minute of entering the fray before Ignacio Scocco levelled just after the hour mark to earn a share of the spoils.
With two games remaining, Newell now sit two points behind Lanus and Velez Sarsfield, who each have a game in hand.
Three points further back in fifth Belgrano Cordoba drew 1-1 at San Martin San Juan.
Belgrano took the lead in the 32nd minute through Victor Aquino, but Jorge Luna levelled a minute before the break.
First-half goals from Denis Stracqualursi and Julio Buffarini gave San Lorenzo a 2-1 win at Argentinos Juniors.
Substitute Gustavo Oberman pulled back a consolation goal in the 70th minute. Walter Kannemann was dismissed in the closing stages for San Lorenzo.
The day's other game was a 2-2 draw between Independiente and River Plate, Jonathan Bottinelli (22) and Carlos Sanchez (61) getting the goals for River in between strikes from Hernan Fredes (4) and Leonel Galeano (71).
Information from the Press Association has been used in this report.