Newell's came from two goals down at Union on Saturday to claim a 2-2 draw, but the result drops the club further off the pace of leaders Velez Sarsfield in Argentina's Apertura table.
After going down 2-0 in the first 33 minutes, Martin Tonso and Ignacio Scocco replied for the visitors to help them leave with a share of the points. However, the result is not good enough for a team that held the league lead only one month ago.
The draw, combined with a 2-0 win for Velez Sarsfield against All Boys, leaves Newell's five points back with two matches remaining, and all but brings an end to their title challenge.
After beating Arsenal, 2-1, on Oct. 27, Newell's has now gone five successive matches without a win, dropping the club into third place.
Velez needed goals from Lucas Pratto and Facundo Ferreyra in the final five minutes to secure its win, and the club now sits two points clear of second- place Lanus, which was held to a 0-0 draw at home against Estudiantes on Sunday.
Boca Juniors secured a 3-1 win against Racing behind two goals from Leandro Paredes, keeping Boca in the hunt for a top-three place, while Tigre got first-half goals from Silvio Gonzalez and Ruben Botta in a 2-0 triumph against Godoy Cruz.
Independiente and River Plate played to a 2-2 draw, San Martin and Belgrano traded goals in the first half of a 1-1 deadlock and San Lorenzo topped Argentinos Juniors, 2-1, courtesy of goals from Denis Stracqualursi and Julio Buffarini.
On Monday, Jorge Ortiz and Diego Braghieri scored two minutes apart to help Arsenal to a 2-1 defeat of Quilmes while Atletico Rafaela claimed a 2-0 win over Colon.