Defensa y Justicia defeated Tigre 2-1, moving into third place in the Superliga Argentina and closing in on league leader Racing Club.
Racing Club, which played to a 0-0 draw against Banfield on Sunday, has 30 points.
Atletico Tucuman is sitting in second place, with 28 points, and Defensa y Justicia, with 26 points, is now in third.
Defensa y Justicia, the big surprise of the tournament, scored first in Monday's match, with Paraguayan Matias Rojas putting his club on the scoreboard in the 5th minute.
Tigre's Walter Montillo tied the score 52 minutes into the match, and Nicolas Fernandez made it 2-1 for Defensa 10 minutes before the end of play.
Tigre, which is in danger of being relegated to the Second Division, was hurt by the expulsions of Ignacio Canuto in the 67th minute and Sebastian Prediger in the 84th minute.
In other action on Monday, Lanus edged Independiente 1-0, reducing the chances that it will be relegated to the Second Division.