Azul y Oro are tied for first in the overall standings with a total of 36 points, while Union dropped down to 23rd in the second-round standings after suffering a 5-1 defeat at home to River Plate.
Match preview
Over their last two domestic encounters, Boca Juniors have come out swinging, tallying eight goals in victories over Tigre (5-3) and Barracas Central (3-1).
Coming into this contest, Sebastian Battaglia's men are unbeaten in their previous 12 matches played in all competitions on their home field.
Only one season has passed since this famous club last captured the domestic crown (2019-20), but even that wait can feel like a long time for a team with a lengthy tradition of winning.
To beat this talented side, it seems imperative that you tally first as their only two defeats in this domestic campaign have come when they failed to draw first blood, going goalless in both of those defeats.
Their offensive pressing is as good as any side in Argentina, forcing opposing centre-backs to make split-second decisions and creating lots of chances from giveaways as a result.
Union continue to struggle at home without a victory in the second phase of this competition, being outscored 7-2 after two matches.
Away from home has been where they have thrived of late, unbeaten in three consecutive road fixtures in all competitions and notching eight goals.
Challenging for the overall league title might be unrealistic at this stage as they sit 15 points back of the top spot, but a win on Friday could vault them back into contention for a Copa Sudamericana spot next year, currently trailing Banfield for that final position by five points.
So far, after four matches in the second phase, Gustavo Munua has yet to fix their defensive issues, with his side conceding the most goals in this round (10).
While rarely playing passively, Union can sometimes be a little over-exuberant going forward and get caught out in transition, with their fullbacks often pushing too high up the field.
Boca Juniors Argentine Primera Division form:
Boca Juniors form (all competitions):
Union Argentine Primera Division form:
Union form (all competitions):
Team News
Boca Juniors striker Exequiel Zeballos is in a five-way tie for the league lead with three goals in this round, as he, Sebastian Villa and Guillermo Fernandez all found the back of the net in their triumph last Sunday, while Frank Fabra picked up two assists.
Eduardo Salvio could be back in the fold after missing time with a muscle problem, Diego Gonzalez might still be a couple of weeks away with his meniscus issue and Norberto Briasco is not expected back until early July because of an ankle injury.
We saw a few changes to their lineup last weekend compared to the team that began against Tigre as Carlos Izquierdoz, Luis Advincula and Oscar Romero replaced Nicolas Figal, Marcelo Weigandt and Aaron Molinas in the starting 11.
Jonathan Alvez has tallied in back-to-back road fixtures for Union with three goals so far, while Mariano Peralta Bauer had the only tally in their defeat to River Plate.
Imanol Machuca assisted on the equaliser that former striker Fernando Marquez scored in their 1-1 draw versus Boca Juniors in 2021.
We saw three new faces in the Union starting 11 in their previous encounter with Diego Polenta, Machuca and Juan Ignacio Nardoni, replacing Emanuel Britez, Leonel Bucca and Alvez.
Boca Juniors possible starting lineup:
Rossi; Fabra, Zambrano, Izquierdoz, Advincula; Varela; Villa, Romero, Molinas, Zeballos; Benedetto
Union possible starting lineup:
Mele; Blasi, Calderon, Polenta, Corvalan; Juarez, Bucca, Nardoni, Zenon; Bauer, Diale
We say: Boca Juniors 3-0 Union
Tatengue are playing Boca Juniors at an inopportune moment with the 34-time league champions firing on all cylinders in the attacking third, while Union might still be a little shell shocked from that second-half performance against River Plate where they conceded four goals in the final half-hour.