A tough run since the beginning of the playoffs has seen the hosts fall behind Club Brugge, while their visitors are winless since the end of the regular season and condemned to a fourth-placed finish in the group.
Match preview
Upon their return to the top flight of Belgian football, Union SG enjoyed an eye-catching regular season, dominating throughout and finishing at the summit prior to the playoffs with 77 points from 34 outings.
With their points halved and rounded up heading into the six-game playoff campaign, Felice Mazzu's side knew they needed to better Club Brugge's tally with a three-point head start, and they made a winning start against Anderlecht before being held to a goalless draw away at Sunday's opponents.
Les Unionistes then headed into a crucial double-header with the capital giants to all but decide who would win the title, and they fell to consecutive defeats, firstly losing 2-0 on home turf before an Anthony Moris own goal meant they were narrowly beaten 1-0 on their travels.
Those results saw them fall three points off top spot with two games to go, and, despite returning to winning ways last time out, with Kaoru Mitoma and Deniz Undav scoring in a 2-0 victory away at Brussels rivals Anderlecht, Club Brugge also took another three-point haul to make the gap unassailable with one match to go.
Having just fallen short of lifting their first Pro League trophy since 1935, Les Unionistes should still be proud of what has been a particularly impressive campaign, and they will hope to end the term on a high with another victory before the promise of another title charge and a place in European competition next term.
Royal Antwerp will arrive looking to put a first win of the playoff stage on the board at the final time of asking, having struggled since finishing in the top four.
Back-to-back wins put the Great Old in fourth spot heading into the final game of the regular season, and a draw with Cercle Brugge was enough to keep them ahead of Gent and book a place in the Championship group for the playoffs.
Brian Priske's side have since struggled, firstly losing to Club Brugge before they were, at least, able to damage Union SG's title challenge with a goalless draw.
Following that point, Antwerp went on to be thrashed 4-0 by Anderlecht and beaten 2-1 in the reverse fixture before falling to a 3-1 home defeat to the retaining champions last time out, with Michael Frey's early opener cancelled out in the second half and later overpowered by goals from Jack Hendry and Sargis Adamyan.
Their tough run since the beginning of the playoffs has seen Priske's men confined to a fourth-placed finish, but, having done well to take a place in the Championship group, they will still be relatively pleased and will look to end with what would be an impressive victory away at the second-placed side.
Union SG Belgian Pro League form:
Royal Antwerp Belgian Pro League form:
Team News
Union SG's line will be led by Brighton & Hove Albion loanee Deniz Undav, who has enjoyed a prolific season in Belgium, netting 27 goals in 40 appearances across all competitions.
He will again be partnered by Dante Vanzeir, while fellow Brighton man Kaoru Mitoma offers further threat in attack from the left-hand side.
Elsewhere, Casper Nielsen and Teddy Teuma have been relative ever-presents in midfield throughout the season, with Lazare Amani again set to take the final spot in the engine room.
Royal Antwerp are expected to remain without former Aston Villa defender Bjorn Engels, who is sidelined by an injury.
Veteran midfielder Radja Nainggolan has continued to be a key man this season, and he will start in the centre if deemed fit.
Michael Frey will continue to spearhead the attack after hitting his 23rd goal of the season last time out.
Union SG possible starting lineup:
Moris; Kandouss, Burgess, Van Der Heyden; Lapoussin, Teuma, Nielsen, Amani, Mitoma; Vanzeir, Undav
Royal Antwerp possible starting lineup:
Butez; Seck, Almeida, Pacho; Miyoshi, Dwomoh, Haroun, Nainggolan, De Laet; Frey, Samatta