In their final match of the season, Lanus struggled to reach top gear against mid-table Newell's, who had the better of the goalscoring opportunities at their Estadio Marcelo Alberto Bielsa, leaving Racing Club and River Plate to battle it out for the championship.
Racing and River will play in the final two games of the season on Sunday, as the rest of the league has already completed their campaigns.
To clinch the title, River (36 points) will have to win at bottom club Quilmes and hope Racing fail to beat 15th-placed Godoy Cruz at home.
Guillermo Barros Schelotto's Lanus (35) needed to beat Newell's to have any chance of claiming the championship but instead barely tested their opposition goalkeeper.
Newell's took 21 shots to Lanus' seven, while the visitors only hit the target twice.
In the other match on Sunday, Boca Juniors - who had been well in the hunt for the title but notched just one win in their last four games - lost 2-0 at home to Gimnasia La Plata.
Jorge Rojas struck the opening goal for Gimnasia and then set up the second in the first minute after half-time for Pablo Vegetti.
The result means Boca finish in fifth with 31 points, two behind fourth-placed Independiente, who lost 4-0 at Belgrano.
That was not the biggest win of the weekend, however, with Arsenal thumping Atletico Rafaela 6-1 with Brahian Aleman notching a brace.
The goals also rained down in La Plata as Estudiantes defeated Tigre 4-2, while Rosario Central trumped Banfield 3-2 in Lomas de Zamora.
In other results, San Lorenzo won 2-0 at Velez Sarsfield and Olimpo were held to a scoreless draw at home by Defensa y Justicia.
