Ahead of the crucial encounter at the BayArena, bundesliga.com has gathered all the pertinent pre-match news and information into one place...
Coach Roger Schmidt's charges put themselves in the driving seat last week by recording a 3-2 away victory in Copenhagen. A win or a draw would be enough for Leverkusen to put their names into the hat for the group stage draw, while even a 1-0 or 2-1 defeat would allow them to progress on the away goals rule.
(back) and Philipp Wollscheid (flu) did not take part in the team's final training session on Tuesday but their participation on Wednesday is not thought to be in doubt. (r.) is the only member of the squad set to be rested as he continues to battle his way back to full fitness.
The visitors will have Swedish international Per Nilsson (pictured) available for the return leg. Coach Stale Solbakken, whose heart famously stopped for eight minutes in 2001, has put the former 1. FC Nürnberg stopper straight into the starting line-up after Nilsson joined following der Club's relegation to Bundesliga 2 in May.
Kießling has scored seven goals in three games in all competitions this season, including one in the Danish capital last week and another against Dortmund on Saturday. If he can keep his purple patch going and find the net early, it would all but put the tie to bed and rubberstamp the Werkself's ticket into the group stages.
Brazilian Claudemir has been a key player since arriving in Copenhagen in 2010. Having played over 100 games domestically, he also has ample experience in the Champions League and has scored against FC Barcelona among others. Bayer will look to limit his supply line to strikers Andreas Cornelius and Bashkim Kadrii.
Roger Schmidt: "They need to get two goals, so we're preparing to face a side that'll take more risks. But we have our own style and we won't change it."
Stale Solbakken: "We're still the underdogs. Leverkusen have a lot of European experience. But if we score the first goal there might be a happy ending for us."
The hosts have won all three of their competitive fixtures so far this term: a DFB Cup first round tie against Waldalgesheim, the first leg in Copenhagen and their opening Bundesliga fixture in Dortmund. By contrast, the Danes are currently third bottom in the Danish Superliga and nursing three straight losses.