Boca Juniors, San Lorenzo and upstarts Tigre are level on 36 points from 18 games while Lanus are two points behind.
Goal difference is not used to decide the champions, meaning that a three-way, or even four-way, tie is possible.
Should two teams finish level, a straightforward playoff will be held, but if three or four teams finish level, a mini-league will be played.
The drama is a welcome boost for Argentine domestic football, which suffers from chronic financial problems, hooliganism and the exodus of top players to Mexico and Europe.
Boca and Tigre both appear to have fairly straightforward games as they are at home to mid-table Colon and Banfield respectively.
San Lorenzo have a tricky visit to Argentinos Juniors and Lanus are at home to provincial side San Martin-Tucuman.
Boca are the country's most popular club and are seen as favourites despite dropping four crucial points in their last four games.
"If we don't make any mistakes, we're going to win the championship," said playmaker Juan Roman Riquelme, whose team have been without injured striker Martin Palermo throughout the campaign.
San Lorenzo led for much of the 19-match campaign but had a poor November when they won only once in four games.
However, successive 4-1 wins over Huracan and Independiente have propelled them back into contention.
"We weren't the best before and today we're not the worst," said coach Miguel Angel Russo.
"We never believed we were superior, although we have always been candidates."
Lanus, who claimed their first domestic title one year ago, and Tigre are both modest outfits who have been involved in a recent shift in the balance of power in Argentine football.
Both clubs, along with Banfield and Arsenal, have become increasingly successful recently while traditional outfits such as Racing Club, Independiente and Rosario Central have struggled.
The weekend's matches will also see defending champions River Plate attempt to avoid finishing bottom after a disastrous campaign that has already interrupted Diego Simeone's previously impressive coaching career.
River must win at Estudiantes and hope that Rosario Central lose to Godoy Cruz to save themselves from complete humiliation.
