After a fine showing on French soil, Les Dogues will arrive at Eden Arena in control of the tie - and with one foot in the new-look group phase.
Match preview
Despite holding out until half time, Slavia Prague conceded twice after the break at Lille's temporary home stadium in Valenciennes, leaving their hopes of progressing from the playoffs hanging by a thread.
Tomas Chory came closest to scoring for the Czech side last week, but suffering a 2-0 defeat means they will have plenty of work to do back on home turf.
Slavia have now lost all three of their meetings with Lille in UEFA competition, having previously been beaten 3-1 and 5-1 in the 2009-10 Europa League, so they must turn that trend on its head at Eden Arena.
Jindrich Trpisovsky's squad impressed in Europe last year, finishing first in their Europa League group and beating Roma en route to becoming the first Czech team ever to top a group table.
They were ultimately knocked out by AC Milan in the last 16, before missing out on their domestic title to city rivals Sparta Prague, which left them facing two qualifiers to reach this season's Champions League.
A 4-1 aggregate win over Union Saint-Gilloise in the third round suggested that the Cervenobili would again be a real force - as did a run of four league wins and one draw for the loss of just one goal; however, they could now miss out on a seat at Europe's top table.
While Slavia's last league fixture was postponed - in order to boost their slim hopes in Europe - Lille were back in action at the weekend, when a 2-0 victory over Angers put them among the early Ligue 1 pace-setters.
It has been a successful start to life at LOSC for new boss Bruno Genesio, who also saw his side build a solid lead at Stade du Hainaut in last week's first leg.
In-form striker Jonathan David put them ahead early in the second half, before setting up Edon Zhegrova's late strike, which leaves Les Dogues very much in the driving seat.
David's dramatic extra-time winner against Fenerbahce had previously helped Lille progress from a tough third-round tie, keeping them on track for their first Champions League group appearance in three years.
Having made an unbeaten start to 2024-25 - and with star man David staying at the club for now - they may fancy their chances of returning to UEFA's top club competition on Wednesday.
Slavia Prague Champions League form:
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Slavia Prague form (all competitions):
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Lille Champions League form:
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Lille form (all competitions):
Team News
Last week, Slavia Prague fielded the same lineup that saw off Union SG in the second leg of their third qualifying round tie, and despite defeat, Jindrich Trpisovsky could again name a similar XI.
Featuring in a back three, Tomas Holes will wear the captain's armband, while Tomas Chory, Lukas Provod and Euro 2024 star Ivan Schranz should start up front. Fellow forwards Mojmir Chytil and Vaclav Jurecka could make an impact from the bench.
Another Czech international, Lukas Masopust played his 200th competitive game for Slavia last time out, and he is set to cover the hosts' right flank.
Meanwhile, Lille will be without Aissa Mandi, who also missed the first leg through suspension, but Edon Zhegrova is available after serving a domestic ban at the weekend.
Ex-Manchester United midfielder Angel Gomes suffered a head injury on Ligue 1's opening matchday and is not ready to return just yet; Nabil Bentaleb is also sidelined, while Brazilian full-back Ismaily must undergo knee surgery.
Having scored 26 times last season and then continued in the same vein this term, Canada striker Jonathan David is again set to link up with Remy Cabella in the final third.
Slavia Prague possible starting lineup:
Kinsky; Holes, Ogbu, Zima; Masopust, Dorley, Zafeiris, Diouf; Schranz, Chory, Provod
Lille possible starting lineup:
Chevalier; Meunier, Diakite, Alexsandro, Gudmundsson; Santos, Andre, Haraldsson, Zhegrova; Cabella; David