Having secured a 2-0 victory when the sides met in last week's reverse fixture, the Uruguayan outfit will be looking to pick up where they dropped off as they eye a place in the last-eight of the continental showpiece.
Match preview
Union suffered a huge blow in their Copa Sudamericana title charge last Tuesday when they fell to a 2-0 defeat against Nacional at the Estadio Gran Parque Central.
The game was sparked to life in the opening four minutes when Franco Fagundez put the hosts ahead before Boston River loanee Leandro Lozano doubled the lead with a 21st-minute strike.
Prior to that, Gustavo Munua's men cruised through the group stages unbeaten, picking up three wins and three draws while scoring 10 goals and conceding two to finish top of Group H.
Union head into Tuesday's game fresh off the back of a comprehensive 3-0 victory over Lanus in the Argentine Primera Division which saw them rise to eighth place in the league standings.
While they will look to carry on the momentum and overturn their two-goal deficit, they face a spirited Nacional side who have won four straight games and seven of their last eight across all competitions.
Pablo Repetto's side will be delighted to have announced their Copa Sudamericana arrival in style following their group-stage exit from the Copa Libertadores.
The Uruguayan outfit picked up two wins and lost three of their six games to collect seven points and finish third in Group C, one point off second-placed Velez in the final qualification spot.
Nacional head into Tuesday in solid defensive form, keeping four consecutive clean sheets while conceding just twice in their last eight outings — both goals coming in the 2-1 loss to Danubio FC on June 5.
The Tricolores are currently second in the Primera Division Apertura standings with 28 points from 15 games, four points off first-placed Liverpool URU.
Union Copa Sudamericana form:
Union form (all competitions):
Nacional Copa Sudamericana form:
Nacional form (all competitions):
Team News
Union will take to the pitch without the services of former Atletico Nacional forward Jonatan Alvez, who is currently from a muscle injury.
The 34-year-old, who scored three goals in his opening three league outings, is set to sit out his fifth consecutive game after coming off injured against Barracas Central on June 15.
Facundo Aguero was key in El Tate's victory over Lanus at the weekend and the 27-year-old should retain his position at the heart of the defence, forming a centre-back pairing with ex-LA Galaxy man Diego Polenta.
As for the visitors, Repetto will be unable to call upon 24-year-old defender Juan Izquierdo, who has been out of action since February through a tibia fracture.
Fellow Uruguay international Renzo Sanchez picked up with a severe muscle problem in January's game against Nublense and remains out of contention for the Tricolores.
Union possible starting lineup:
Moyano; Esquivel, Poleta, Aguero, Gerometta; Juarez, Portillo, Nardoni, Machuca; Canete, Gallegos
Nacional possible starting lineup:
Rochet; Lozano, Marichal, Laborda, J. Rodriguez; Castro, Y. Rodriguez, Carballo, Zabala; Gigliotti, Fagundez
We say: Union 1-1 Nacional
Nacional are in the driving seat in this one following last week's first-leg victory. While Union will hope their home advantage can help in their quest to overturn the deficit, they have managed just one win in their last four games at the Estadio 15 de Abril. We predict the Uruguayan side will hold the hosts to a share of the spoils and go through on aggregate.