With three points separating four teams and only one able to stay up, the relegation battle will go to the wire but after Patronato missed the opportuntity to almost guarantee their safety on Saturday, Belgrano failed to take advantage with defeat to Lanús on Sunday.
Some woeful defending from former Lanús centre back Marcelo Herrera allowed José Sand to race in behind with only four minutes on the clock and the 38-year-old made no mistake in slotting past César Rigamonti.
It was a deserved lead for the home side, who had come close on a number of occasions during a flat first half from a Belgrano side so perilously close to dropping back out of the top flight. That changed within seconds of the restart when a hopeful long ball forward released Cristian Techera to equalise but rather than spark a rousing second half display Lanús remained in charge.
Marcelino Moreno sliced through the Belgrano defence to restore the lead and as Belgrano struggled to draw level for the second time, their hopes were dashed five minutes from time when Joaquín Novillo was sent off.
With a man advantage, Guillermo Acosta added a third on the counter and while Lanús finish the round up in the Copa Sudamericana spots, Belgrano are praying for results to go their way next weekend.
Final day fixtures
Patronato v Argentinos Juniors
San Martin de San Juan v Talleres
River Plate v Tigre
Belgrano v Godoy Cruz