Old rivals Boca Juniors frustrated River Plate's attempts to close the gap at the top of the Clausura as the Buenos Aires rivals played out a 1-1 draw at Boca's La Bombonera stadium on Sunday.
River Plate, who started the game five points behind leaders Lanus, took a first minute lead through Manuel Lanzini, but Santiago Silva levelled it up six minutes before the break.
Trouble erupted in the stands in the second half, causing a temporary halt to the action, and the bad blood was felt on the pitch too in the final minute when Boca defender Guillermo Burdisso was sent off.
Adrian Fernandez's first-half brace gave Independiente a 2-0 away win over Tigre with goals in the ninth and 40th minutes.
Atletico Rafaele played an hour with 10 men but still managed to come from behind with two late goals and beat San Martin San Juan 2-1.
Things were looking grim for Atletico after Lucas Landa put the visitors ahead in the 17th minute and then Matias Fissore saw red on the half-hour mark.
But Federico Gonzalez levelled it in the 84th minute and then snatched a winner from the penalty spot in the 89th minute.