The Austrian crop fell to a 2-1 loss to their Belgian counterparts on matchday three, leaving them at the foot of the section and their visitors two places and four points better off.
Match preview
As was the case in their Europa League opener with Liverpool, LASK Linz entered half time a goal to the good during their meeting with Union SG two weeks ago, as Moses Usor sought to get his side off the mark in Group E at the third attempt.
LASK clung onto their slender advantage for the majority of the second half, but Cameron Puertas's 84th-minute penalty drew Union SG level before the Belgian team snatched victory from the jaws of defeat, breaking Linz hearts through Christian Burgess's injury-time header.
With all of their hard work being undone in an excruciating 10-minute period, Thomas Sageder's team enter matchday four of the 2023-24 Europa League as one of only two teams without a point on the board at the halfway mark - the other being BK Hacken - having also fallen to Liverpool and Toulouse's superiority thus far.
Should the hosts suffer a fourth continental defeat on the bounce and Toulouse clinch a shock win over Liverpool, LASK will be consigned to a fourth-placed finish in Group E, although a positive result would at least keep their chances of a knockout round playoff or Europa Conference League berth alive.
A new page of unwanted club history could also be written for Sageder's side, who have never lost four European matches on the trot before, but a 3-1 Austrian Bundesliga win over fellow powerhouses Sturm Graz at the weekend should at least provide an injection of confidence.
An injection of confidence is exactly what Union SG received on matchday three as they kept their fleeting hopes of a first-placed finish alive, having only gleaned one point from a possible six versus Toulouse and Liverpool before leaving it late on October 26.
That smash-and-grab victory represents the visitors' second triumph in an eye-catching six-game winning run across domestic and continental competition, and Union SG prolonged the feel-good factor with a hard-fought beating of the esteemed Club Brugge over the weekend.
Mohamed Amoura was the hero of the hour for Alexander Blessin's team, netting either side of a Maxim De Cuyper strike to ensure maximum spoils for Union SG, whose substitute striker Kevin Rodriguez breathed a sigh of relief as his late penalty miss proved inconsequential.
Boasting an unassailable four-point lead at the top of the Jupiler Pro League table, Union SG will be guaranteed a top-three finish if they overcome LASK for the second time in a row this week, while also ensuring that Liverpool cannot sail off into the last-16 sunset just yet.
The Belgian upstarts have also made the net ripple at least twice in each of their last six wins, but they have often been forced to fight fire with fire owing to defensive deficiencies; Blessin's side have gone through each of their last five games without a clean sheet.
LASK Linz Europa League form:
W
D
L
L
L
LASK Linz form (all competitions):
Union SG Europa League form:
W
W
D
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W
Union SG form (all competitions):
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Team News
LASK Linz's evening went from bad to worse against Union when goalscorer Usor was taken off with a second-half injury, but the winger recovered in time to break the deadlock against Sturm Graz at the weekend.
The hosts' ranks remain ravaged, though, as Adil Taoui and Tobias Anselm are both recuperating from ACL problems, while Ebrima Darboe, Branko Jovicic, Rene Renner and Philipp Wiesinger are also sidelined for the time being.
Star striker Robert Zulj will sit out his side's meeting with Liverpool on November 30 if he is cautioned on Thursday, but the captain should continue to act as the focal point after scoring one and setting up two more in the victory over Sturm Graz.
As for Union SG, their beating of Club Brugge at the weekend came at a cost, as two-goal attacker Amoura and midfielder Lazare Amani were both forced off within two minutes of one another in the second half.
Updates on the duo's condition have been scarce, although Amani is not believed to be nursing a serious problem and should be in contention for this week, which is more than can be said for Gustaf Nilsson and his hamstring concern.
Despite fluffing his lines from the spot in injury time at the weekend, Rodriguez could be afforded an opportunity up top if Amoura is not passed fit for matchday four.
LASK Linz possible starting lineup:
Lawal; Zieris, Andrade, Taloverov; Stojkovic, Horvath, Ljubic, Bello; Flecker, Zulj, Usor
Union SG possible starting lineup:
Moris; Mac Allister, Burgess, Machida; Castro-Montes, Amani, Puertas, Vanhoutte, Lapoussin; Rodriguez, Eckert Ayensa
We say: LASK Linz 1-1 Union SG
With uncertainty lingering over Amoura's availability, Union SG may not make lightning strike twice against LASK Linz, who could count themselves unfortunate not to come away with at least a draw on matchday three.