Estudiantes and Velez both secured victories on Wednesday, meaning the Argentina Apertura title will go to one of the clubs in the final round on Sunday.
Estudiantes racked up an emphatic 4-0 victory over River Plate before 50,000 at River's Monumental stadium with goals from Leandro Desabato, Matias Sanchez, Marcos Rojo and Gabriel Mercado.
Velez was more modest, defeating Huracan 2-0 on a second-half goals by Jonatan Cristaldo. Estudiantes improved to 42 points and Velez has 40. If the teams tie on points, a one-game playoff will determine the title. Estudiantes face Arsenal on Sunday and Velez plays Racing.
The final round of games concludes on Monday.
Estudiantes took the lead on a third-minute goal by Desabato, who scored with a header from a free kick by Leandro Benitez.
River Plate almost got the goal back in the ninth minute when Erik Lamela's free kick hit the post with a shot that had beaten Estudiantes goalkeeper Agustin Orion.
After that is was all Estudiantes.
Sanchez made it 2-0 in first-half stoppage time, chipping in a cross from six meters (yards) that beat River keeper Juan Pablo Carrizo.
Rojos scored in the 48th, taking advantage of a defensive mixup, and Mercado became the fourth different scorer in the 57th.
Estudiantes played the match without its top player, midfielder Juan Sebastian Veron, who picked up a yellow card in the previous match and was serving a one-game ban.
The lopsided loss could be critical for River Plate, which faces a possible relegation battle to avoid the drop to the second division. Relegation in Argentina is determined on results over three seasons.
Cristaldo scored the two goals knowing Estudiantes - which was playing at the same time - was leading and could claim the title if Velez failed to win.
In a late match Wednesday, Godoy Cruz and Racing drew 1-1. Jairo Castillo scored for Godoy and Ivan Pillud for Racing.
Following Estudiantes and Velez in the standings are Arsenal with 32, Racing with 29 and River with 28.
In two 18th-round matches Tuesday, Gimnasia defeated All Boys 3-1 and Arsenal won over Colon 2-1.
