The teams meet at Stade du Hainaut in Valenciennes, as Lille's home stadium is still not available after the Olympics, and both will seek an advantage to take into next week's second leg.
Match preview
Leading by one goal from the first leg in France, Lille visited Turkish giants Fenerbahce at Sukru Saracoglu Stadium last week, and much to Jose Mourinho's obvious displeasure they inched through at the end of extra time.
Les Dogues progressed with a 3-2 aggregate scoreline thanks to Jonathan David's dramatic 118th-minute winner, which secured a precious place in the Champions League playoffs.
Having missed out on third place in Ligue 1 last term by conceding a stoppage-time equaliser on the final day, meaning automatic qualification slipped through their fingers, Lille are now within a whisker of making the group phase for the first time in three years.
After leading LOSC to fourth spot, former coach Paulo Fonseca departed for AC Milan during the summer, so now new boss Bruno Genesio is overseeing their latest attempt to reach UEFA's top club competition.
This year's expanded format would ensure at least eight high-profile games through to January, but they must again miss out on home advantage in the all-important playoffs.
With Stade Pierre Mauroy still out of action, Genesio's men kicked off their league campaign with a 2-0 away win over Reims on Saturday evening, when David scored during second-half stoppage time. Now, they aim to replicate a previous Lille side's successes against Slavia Prague.
When these clubs met in the Europa League group stage some 15 years ago, Lille easily took three points from both encounters, winning 3-1 and 5-1 in the autumn of 2009.
Jindrich Trpisovsky's current squad will expect to fare far better this time around, having impressed in Europe last year and then been narrowly beaten to the Czech title by city rivals Sparta Prague for a second straight season.
Slavia's consolation prize was a place in the Champions League qualifiers, and victory in their opening tie was virtually wrapped up with a 3-1 first-leg win over Union Saint-Gilloise in the third round.
Six days later, they finished the job in Belgium, and following Vaclav Jurecka's late goal, a 4-1 aggregate scoreline saw them reach the penultimate hurdle of qualifying.
The Cervenobili have been back in action since last month, when they kicked off their domestic campaign with a disappointing 0-0 draw at Slovacko, but four subsequent wins for the loss of just one goal have since left them only two points shy of Sparta in the First League standings.
Last year, Slavia finished first in their Europa League group with 15 points, beating Roma en route to becoming the first Czech team ever to top a group table, but ultimately went out to AC Milan in the last 16. Just a few months later, they are determined to dine at Europe's top table.
Lille Champions League form:
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Lille form (all competitions):
Slavia Prague Champions League form:
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Slavia Prague form (all competitions):
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Team News
Bruno Genesio must make at least two changes to the Lille side that lined up in Reims at the weekend, as centre-back Aissa Mandi will serve a suspension for his stoppage-time dismissal against Fenerbahce and ex-Manchester United midfielder Angel Gomes suffered a serious head injury.
Several players were rested on Saturday, but Thomas Meunier, Hakon Haraldsson and Jonathan David should all return to the starting XI in midweek.
David scored 26 times across all competitions last season and has started sharply this term; the Canada international is set to link up with Haraldsson and Remy Cabella in the final third.
Slavia's main summer signing Tomas Chory struck twice in the third qualifying round and is among several contenders to feature in the visitors' attacking trident.
Chory's fellow Czech internationals Mojmir Chytil and Lukas Provod join Slovakia's Euro 2024 star Ivan Schranz in vying for selection, while Vaclav Jurecka cannot be counted out.
Meanwhile, Oscar Dorley and Christos Zafeiris both scored in Saturday's 2-1 league win over Teplice, and they should feature alongside captain Lukas Masopust in midfield.
Lille possible starting lineup:
Chevalier; Meunier, Diakite, Alexsandro, Gudmundsson; Santos, Mukau, Andre; Cabella, Haraldsson; David
Slavia Prague possible starting lineup:
Kinsky; Holes, Ogbu, Zima; Masopust, Dorley, Zafeiris, Diouf; Schranz, Chory, Provod
We say: Lille 1-0 Slavia Prague
Slavia Prague have conceded just twice in seven competitive games this season, so Lille have their work cut out to secure a first-leg lead.
The Ligue 1 club should just come out on top against a well-drilled away side, though, leaving this tie tantalisingly poised ahead of next week's return.