The visitors, meanwhile, head into the encounter winless in their last two games, but seven points clear of their forthcoming opponents in the table.
Match preview
Having picked up only nine points from their opening 15 games of the season, Union have improved in recent weeks, with Gustavo Munua's side beating Central Cordoba and Huracan both by the scoreline of 1-0.
Enzo Roldan's 87th-minute winner away to Central Cordoba may prove to be the turning point in El Tate's campaign, with Munua's side winning on the road once again courtesy of Mauro Luna Diale's strike against Huracan.
With Union finding themselves second from bottom ahead of their home match against Gimnasia this weekend, Munua will recognise that his team are at risk of succumbing to relegation, although there is still an awfully long way to go until those matters are settled.
Regardless, the 45-year-old will be demanding far more from his players after finishing 12th under his guidance last season, and registering a third consecutive win on Sunday would certainly signal a return to form for the Santa Fe-based outfit.
Gimnasia, meanwhile, have not made the greatest start to life under the management of Sebastian Ariel Romero, who previously led the reserve team after calling an end to his playing career in 2018.
The 45-year-old, who earned one cap for Argentina as a player, is embarking on his first ever senior managerial role having been appointed earlier this year, and it has been a steady if unspectacular start to what he will hope turns out to be a long and illustrious career as a manager.
Like their forthcoming opponents, Gimnasia registered back-to-back 1-0 wins against Arsenal Sarandi and Lanus earlier in May, but they have been unable to score against Godoy Cruz or Sarmiento more recently in the league.
However, they did defeat Colombian side Santa Fe 1-0 in the Copa Sudamericana last week, which revived their hopes of making it to the knockout stages of South America's secondary continental competition.
In the meantime, Romero will be hoping to see his players return to winning ways domestically against Union on Sunday, in what is likely to be a tight affair based on both teams' recent results.
Union Argentine Primera Division form:
D
L
D
L
W
W
Gimnasia Argentine Primera Division form:
W
D
W
W
L
D
Gimnasia form (all competitions):
L
W
W
L
W
D
Team News
Union appear to have a fully fit squad at their disposal at present, making it unlikely that Munua will tinker with a winning team having finally found a successful formula in recent weeks.
That could mean Roldan appearing from the bench once again, despite his goalscoring heroics in his side's previous match against Central Cordoba.
Gimnasia, meanwhile, will travel without Benjamin Dominguez, Lautaro Chavez and German Guiffrey due to injuries, limiting Romero's ability to rotate his team.
However, both sides have had plenty of rest since their last match, and Romero will have taken plenty of positives from his side's performance against Sarmiento last time out, even if they were held to a goalless draw by their opponents.
As such, he may pick the same starting XI that generated 21 shots and 66% possession across the course of the encounter.
Union possible starting lineup:
Mele; Vera, Paz, Calderon, Corvalan, Esquivel; Comas, Mosqueira, Luna; Machuca, Domina
Gimnasia possible starting lineup:
Durso; Schelotto, Morales, Sanchez, Melluso; Soldano, Mamut, Bolivar, Lescano, Ramirez; Tarragona
We say: Union 1-0 Gimnasia
We do not expect there to be many goals between these two sides, who have both looked to keep things tight recently.
Union appear to be finding their groove lately, though, so we can envisage another 1-0 victory for Munua's side.