San Lorenzo coach Diego Simeone handed in his resignation immediately after seeing his side stumble to a 1-0 defeat against Gimnasia La Plata.
Sebastian Romero scored the only goal of the game after just five minutes to send San Lorenzo to their seventh defeat of the Clausura season and leave them fourth from bottom in the standings.
Simeone, who was roundly booed after the game, was days away from completing a year in charge of San Lorenzo and was quoted as telling Ole: "It's the best thing for the club".
Expectations were high at San Lorenzo after the appointment of the former Argentina international, who won league titles as coach of Estudiantes in 2006 and River Plate in 2008, but success failed to materialise. Former Mexico coach Ricardo La Volpe has emerged as a strong candidate to take over.
"The decision was Simeone's, although it's by mutual accord with the directors," club Vice President Guillermo Zoppi was quoted as saying.
At the other end of the table Independiente continued their march towards the title with a 1-0 victory at home to Arsenal Sarandi.
Leonel Nunez netted on the half-hour mark to see Independiente maintain their five-point lead over Argentinos Juniors, who triumphed 2-1 over Chacarita Juniors. Facundo Coria grabbed a first-half brace for the hosts before Omar Zarif gave Chacarita hope in the 71st minute.
Elsewhere, Newell's Old Boys fell to a 2-0 loss against Tigre. Juan Pablo Garat gave the visitors the lead in the fourth minute and Braian Rodriguez all but sealed the result in the 71st minute.