Gimnasia La Plata coach Diego Cocca resigned from his post after his side lost 2-0 to Estudiantes in the La Plata derby, a result which saw the hosts go top of the Apertura.
Federico Fernandez (37) and Juan Sebastian Veron's 45th-minute penalty earned the win, which elevated Estudiantes to a two-point lead over Velez Sarsfield after eight matches.
Gimnasia had Fabian Rinaudo sent off two minutes from time.
"We tried everything we could but a change of air is necessary (for Gimnasia) to get out of this situation," Cocca told reporters. "We'll be urging the team on so they stay in the first division."