A nail-biting finale could be in store for both sides, who are only separated by one place in the rankings after four matches, but a victory for the French outfit would seal both teams' fates.
Match preview
Two weeks on from a humbling 5-1 beatdown on the Anfield turf, the stage was set for Toulouse to be dismantled by Liverpool once again at Stadium Municipal, having followed up their initial loss to the Reds with dampening Ligue 1 losses to Montpellier HSC and Le Havre.
However, as Jurgen Klopp's men produced arguably their worst display of the season so far, Toulouse took full advantage through Aron Donnum, Thijs Dallinga and Frank Magri in an engrossing 3-2 victory, although a few hearts were in mouths when Jarell Quansah had the ball in the net in injury time, only for the defender's goal to be ruled out.
Denying Liverpool the chance to seal a first-placed finish while keeping their own chances of a last-16 place alive, Toulouse enter matchday five just two points behind the Reds in second place and need LASK Linz to do them a huge favour if they are to usurp Liverpool ahead of the final gameweek.
While Toulouse's hopes of a LASK win at Anfield are unfounded, Carles Martinez's side will book a ticket to the knockout round playoffs at worst if they get the better of Union SG this week, but defeating Liverpool was not the catalyst for change that the Violets faithful had prayed for.
Upon the return of domestic football, Toulouse had no answer to Nice's defensive diligence at the weekend - although many Ligue 1 teams have failed to break down Les Aiglons this term - as Terem Moffi condemned Martinez's men to a 1-0 loss, meaning it is just one win from their last eight for the reigning Coupe de France champions.
Similarly to Toulouse's surprise beating of Liverpool, Union SG's clash with LASK Linz on matchday four did not follow the pre-game script either, as the Belgian side travelled to their winless and pointless Austrian foes on the back of five successive wins in all tournaments.
The form book was well and truly ripped up at the Raiffeisen Arena, though, as Robert Zulj, Sascha Horvath and Maksym Taloverov all breached the Union SG backline in an eye-catching 3-0 victory for LASK, who blew Group E wide open and prolonged their visitors' misery on the road.
Losing both of their away games in the 2023-24 Europa League group stage so far by an aggregate scoreline of 5-0, Union SG have their home exploits to thank for their current third-placed position, but they are just one point above LASK and will be eliminated from top-two contention if they lose on Thursday.
Alexander Blessin's men returned from the international break with a tantalising Jupiler Pro League clash away to Gent at the weekend, where they fought back from a goal down to salvage a point in a 1-1 draw - remaining top of the table in the process - and they held Toulouse to a stalemate in identical circumstances in September.
Attacking proficiency has been hard to come by since the exit of Victor Boniface to Bayer Leverkusen, though, as Union SG have scored three goals in Group E from an expected 5.9 - no other team in the Europa League is under-performing their xG as much in the current campaign.
Toulouse Europa League form:
D
W
L
W
Toulouse form (all competitions):
L
L
L
W
D
L
Union SG Europa League form:
W
W
D
L
W
L
Union SG form (all competitions):
W
W
W
L
W
D
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Team News
Toulouse head coach Martinez will receive two timely boosts ahead of the visit of Union SG, as Dallinga - now a Netherlands international - is back from suspension, as is German playmaker Niklas Schmidt, who could not strut his stuff against Nice on account of an accumulation of bookings.
Dallinga - who has netted in three of the hosts' four European games so far this term - should demote Magri down to the bench straight away, while Warren Kamanzi's place in the XI will come under threat from the returning Schmidt.
Zakaria Aboukhlal (knee) and Oliver Zanden (hip) should be the only players missing through injury for Les Violets, who may recall Moussa Diarra to the backline after the 23-year-old played a crucial role in their beating of Liverpool three weeks ago.
Meanwhile, the Union SG squad is also in rather good nick heading into Thursday's crucial encounter, and Blessin may even be blessed with a fully fit squad, as no injuries have been reported from their stalemate with Gent.
Charles Vanhoutte is walking a tightrope, though, as one more booking will rule the midfielder out of Union SG's final group game against Liverpool, but the 25-year-old has started 20 of his side's 22 matches this season and is unlikely to drop out of the XI.
However, should Blessin opt not to take any risks with Vanhoutte, either Noah Sadiki or Mathias Rasmussen will be called upon to join Lazare Amani in the visitors' 3-4-1-2 setup.
Toulouse possible starting lineup:
Restes; Desler, Costa, Nicolaisen, Diarra; Donnum, Sierro, Casseres Jr, Suazo; Schmidt, Dallinga
Union SG possible starting lineup:
Moris; Mac Allister, Machida, Burgess; Castro-Montes, Amani, Vanhoutte, Lapoussin; Puertas; Amoura, Eckert Ayensa
We say: Toulouse 2-1 Union SG
With their penchant for profligacy in the Europa League well-documented, Union SG will struggle to fight fire with fire on Toulouse's turf, where Les Violets have only been beaten in one of their last nine competitive matches.