The away side, on the other hand, head into this one in scintillating form as they go in search of a fifth victory in six matches.
Match preview
Estudiantes were knocked out of this year's Copa Argentina by Central Cordoba following a 2-1 defeat in Wednesday's round-of-32 meeting.
Goals in both halves from Rodrigo Atencio left Eduardo Dominguez's men with work to do although they did manage to pull one back through Pablo Piatti, albeit all to no avail.
This came in the aftermath of a 2-0 defeat against Sarmiento Junin which saw Los Pincharratas drop to 14th place in the Argentine Primera Division table.
Coming up next is the challenge of an opposing outfit who boast just two wins from the last nine editions of this fixture, losing six of the remaining seven.
Aiming to pick up what would be a first win on home turf since May, Sunday's hosts will be keen to give their fans reason to cheer off the back of a tough couple of weeks.
Union made it three wins on the spin as they narrowly pipped San Lorenzo to a 2-1 victory at Estadio 15 de Abril on June 15.
Alexis Cuello's 36th-minute strike left Kily Gonzalez's men trailing at half time before second-half goals from Franco Pardo and Gonzalo Morales completed a remarkable turnaround.
With 13 points points amassed from five league matches this term, El Tate sit fourth in the standings but are level on points with leaders Talleres Cordoba.
Unbeaten in nine of 10 away involvements dating back to mid-January, Sunday's visitors will fancy their chances of getting something out of their trip to La Plata this weekend.
Estudiantes Argentine Primera Division form:
W
W
W
L
D
L
Estudiantes form (all competitions):
W
L
L
D
D
L
Union Argentine Primera Division form:
W
W
D
W
W
W
Team News
Estudiantes' Javier Altamirano has been sidelined for the past four months and the midfielder is unavailable for selection here.
Eric Meza is also ruled out for the home side as he prepares to sit out a fourth successive game with a muscle problem.
Pablo Piatti found the back of the net less than 20 minutes after coming on as a substitute last time out which could see him rewarded with a place in the starting XI.
Francisco Gerometta and Patricio Tanda will not play any part for Union in this one as they continue to nurse long-term injuries.
However, Bruno Pitton is eligible to feature for the away side once again having served a one-game suspension in the win over San Lorenzo.
Estudiantes possible starting lineup:
Mansilla; N.Fernandez, F.Fernandez, Lollo, Mancuso; Perez, Piatti, Sosa; Angulo, Palacios, Correa
Union possible starting lineup:
Campisi; Vera, Paz, Pardo, Corvalan, Del Blanco; Pitton, Mosqueira, Diale; Orsini, Domina