The Greek outfit established a 1-0 advantage from the first leg and will now look to guarantee continental football for 2023-24 in the reverse fixture.
Match preview
From losing the Belgian top-flight title in the final seconds of 2022-23 to exiting the Champions League in the second qualifying round earlier this month, it has been a few months to forget for Genk.
Accumulating six points from their three league fixtures for this season can be considered to be a positive, yet the focus is now on ensuring that they have some European football to look forward to for the remainder of the calendar year.
Regardless of what happens in this tie, the Europa Conference League playoffs is the prize for the loser, but Genk will want to do everything possible to remain in this competition.
A first-minute goal from Kostas Fortounis proved to be the difference in the first leg, Olympiacos prevailing in what was their first competitive game of the season.
On some level, both teams will be content with the outcome, yet it is worth noting that Genk have failed to win any of their last four competitive matches at the Cegeka Arena.
The pressure is now on Wouter Vrancken to deliver a turnaround on Thursday night, the prize on offer a tie with Serbian side FK Cukaricki.
From Olympiacos' perspective, they may have preferred to build on their triumph last week with a fixture at the weekend.
However, Diego Martinez will also feel that the benefits can come from his side being well-rested, in comparison to Genk having to battle their way to a 1-0 victory at Cercle Brugge.
While Martinez will have one eye on the top-flight opener with Panserraikos at the weekend, his priority right now will be on ensuring that his team come through the encounter in Belgium without suffering defeat.
Genk Europa League form:
L
Genk form (all competitions):
Olympiacos Europa League form:
W
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Genk duo Matias Galarza and Mike Tresor both missed the game with Cercle Brugge after picking up injuries in the first leg and can be regarded as huge doubts here.
However, Joris Kayembe shook off an issue from the same fixture to start at left-back at the weekend, leaving Aziz Ouattara and Christopher Bonsu Baah who may prove to be the two introductions to the side.
Barring any selection issues, there is little reason for Martinez to tinker with his Olympiacos XI, who have had time to recover from last week's efforts.
While new signing Jackson Porozo will expect to feature regularly this campaign, the Ecuador international seems unlikely to be drafted into the side for this contest.
Pep Biel is arguably the most likely to be drafted into the team on the back of his 10 goals and four assists from attacking midfield in 2022-23.
Genk possible starting lineup:
Vandevoordt; Munoz, McKenzie, Cuesta, Kayembe; Ouattara, Hrosovsky; Paintsil, El Khannouss, Bonsu Baah; Arokodare
Olympiacos possible starting lineup:
Paschalakis; Rodinei, Retsos, Freire, Quini; Camara, Iborra; Masouras, Carvalho, Fortounis; El Arabi
We say: Genk 1-1 Olympiacos (Olympiacos to win 2-1 on aggregate)
Although Genk were able to get back to winning ways at the weekend, it remains to be seen whether their hectic schedule will benefit or hinder them against opponents who have played fewer competitive fixtures. For us, Olympiacos will be well-rested for this game and that could prove to be the difference.