Such is the Argentine league setup that Tigre find themselves in the relegation zone while dominating the early rounds of the Clausura championship in which they are unbeaten with 14 points from six matches.
The drop in Argentina is decided on teams' average points over three seasons - which amounts to six championships with Apertura and Clausura.
The bottom two, where Tigre currently lie, in the parallel relegation standings go down automatically. The teams in 17th and 18th place play off against rivals from the second-tier Primera B Nacional for their top flight survival, which is where River Plate came unstuck last June.
Striker Mauro Boselli headed Estudiantes in front from a 17th-minute free-kick by Leandro Benitez but 10 minutes later, midfielder Diego Morales equalised from the penalty spot after being fouled by defender Cristian Cellay.
"We did all we could, they put a lot of pressure [on us], it wasn't easy to get the ball," Morales told reporters.
"We'll keep fighting, with humility we can get out of it," he added referring to Tigre's dire position in the relegation standings.
Tigre, a modest team from the Buenos Aires suburb of Victoria, remain two points ahead of Estudiantes and Velez Sarsfield, who were held 3-3 by Union in a thriller in Santa Fe.
Velez fell behind to a 18th minute goal by defender Rodrigo Erramuspe before scoring twice before half-time with a penalty by forward Juan Manuel Martinez and a strike from outside the box by midfielder Ivan Bella.
Former Argentina midfielder Federico Insua put Velez 3-1 ahead in the 53rd minute finishing off the best move of the match. Martinez headed down a cross into the box and Insua powered the ball home.
However, Union fought back with two goals in the last 25 minutes. Erramuspe headed home a corner to the far post and striker Pablo Magnin prodded a loose ball home with 10 minutes remaining.
