The hosts currently occupy fourth place with just 13 points, trailing their visitors, who sit two places above them in the table with 14 points, by a single point.
Match preview
After a strong start to the season, with three wins and a draw from their opening four matches, Racing Club have struggled for consistency in recent weeks, losing twice and winning once in their last three.
Gustavo Costas's side bounced back from their first defeat of the campaign against Lanus with a comfortable victory over Godoy Cruz, but they were unable to build on this momentum, suffering a 1-0 loss to mid-table Sarmiento.
La Academia are level on points with fifth-placed Instituto ACC, but ahead on goal difference, while they are two points behind league leaders Huracan.
Racing boast the division's best attack so far, having scored 15 goals in seven matches - however, a concern for Costas will be their failure to find the net in two of their last three games.
The 18-time league champions have a perfect home record, winning all three matches played, scoring seven goals and conceding none, and they will be looking to extend this impressive run on Sunday.
However, their last encounter against their upcoming opponents ended in a 1-0 defeat at home, and a repeat of this result could see them slip further down the table in the second phase and the overall standings.
Union remain unbeaten in the second phase of the Argentine Primera Division following a goalless draw with Estudiantes at Estadio Jorge Luis Hirschi last Sunday.
Kily Gonzalez's side have won four and drawn two of their six matches, and they trail table-toppers Huracan by a point, albeit with a game in hand.
El Tate currently sit sixth in the overall standings, four points off the top, but they will be aiming for a Copa Libertadores place by the end of the season.
With an unbeaten record in 10 of their last 11 away games dating back to mid-January, Sunday's visitors will be confident of securing a positive result in Avellaneda this weekend.
Racing Club Argentine Primera Division form:
W
W
W
L
W
L
Racing Club form (all competitions):
W
W
W
L
W
L
Union Argentine Primera Division form:
W
D
W
W
W
D
Team News
Racing will remain without the injured Fernando Prado (ACL), Agustin Garcia Basso (ankle) and Bruno Zuculini (muscle), who are not expected back in action until next month.
Marco Di Cesare is with Argentina's Olympics team, which will see him miss a considerable number of games depending how far the team goes in the competition.
Union will be without Nicolas Paz whose yellow card against Estudiantes saw him pass the yellow card threshold and will see him miss this clash through suspension.
The striking duo of Adrian Balboa and Nicolas Orsini have scored one goal each so far, but they are expected to start up front once again.
Racing Club possible starting lineup:
Arias; Colombo, Sosa, Quiros; Torres, Nardoni, Almendra, Rojas; Salas, Martinez, Carbonero
Union possible starting lineup:
Campisi; B. Pitton, Paz, Pardo, Corvalan, Vargas; M. Pitton, Mosqueira, Rivero; Orsini, Balboa
We say: Racing Club 1-1 Union
Racing Club have won three of the last five meetings between the two sides, but they lost the most recent encounter on home soil.
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