Facundo Ferreyra scored a second-half winner in only his second start of the season as Banfield claimed a 1-0 victory over struggling Arsenal Sarandi.
Banfield's Jorge Daniel Achucarro had the best chance of the first half when he volleyed a cross over the bar from eight yards out.
However, the Paraguayan atoned for his mistake after the break when he backheeled a 63rd-minute pass from Diego de Douza into the path of Ferreyra, who shrugged off the attention of defender Ignacio Boggino and beat Cristian Campestrini with a fierce shot inside the keeper's near post.
Marcelo Quinteros could have doubled the lead following a breakaway move but his powerful strike from the edge of the area missed the target.
The result ended a four-match winless streak for Banfield, which moves up three places to 10th, while Arsenal remains in 17th place.