Estudiantes take top spot in Argentina
The South American champions have 33 points from 16 matches after River defender Facundo Quiroga headed into his own goal trying to clear a cross from winger Enzo Perez midway through the first half.
Frustrated River, unable to repeat the winning performance of new coach Angel Cappa's debut last weekend, had teenage striker Daniel Villalva and defender Gustavo Cabral sent off in the last three minutes, both for studs-up tackles.
Independiente fell two points behind after a 0-0 draw with Huracan and joined Godoy Cruz, who beat Chacarita Juniors 1-0 on Friday, on 31.
Uruguayan striker Joaquin Boghossian scored twice as sixth-placed Newell's Old Boys crushed Colon 5-0 in Rosario.
Estudiantes, fighting on two fronts, travel to Mexico in midweek to meet San Luis in the first leg of their Libertadores Cup first knockout round tie as they continue to defend their South American title.