Argentine club Arsenal missed a chance to move within striking distance of league leader Boca Juniors in a 2-0 loss to San Lorenzo on Sunday.
San Lorenzo's goals came from Juan Salgueiro and Manuel Gigliotti. The loss kept Arsenal on 19 points, five behind Boca Juniors.
In other Sunday matches, Union defeated Olimpo 2-0, and Argentinos Juniors and Rafaela played a scoreless draw.
Jorge Velazquez and Matias Donnet scored second-half goals in Union's victory.
Boca Juniors stayed on top with a 1-0 victory over Colon on Saturday with Santiago Silva scoring in the 35th minute.
Boca finished with nine players and Colon with 10.
Boca's Juan Insaurralde was sent off in the 40th minute and teammate Clemente Rodrigeuz went off in the 79th for his second yellow card. Colon went down to 10 men in second-half stoppage time when Ivan Moreno y Fabianesi was sent off.
Tigre could move within a point of Boca with a victory on Monday at Belgrano to wrap up the 12th round.
