RB Leipzig will be without playmaker Emil Forsberg amid a trio of injuries for Wednesday's crunch Champions League clash at home to Besiktas.
The Sweden international is suffering from an abdominal injury, while midfielder Marcel Sabitzer has a shoulder injury and teenage French defender Dayot Upamecano has a thigh problem.
The injuries present coach Ralph Hasenhuettl with a setback as the Germans already have it all to do in their attempt to reach the knock-out stage.
Leipzig are third in Group G, level with Porto on seven points, going into their final group game.
The Germans must pick up more points against group winners Besiktas than Porto do at home to eliminated Monaco if they are to snatch second spot.
If they pull it off, the Germans will reach the last 16 in their first Champions League campaign.
Hasenhuettl challenged his side to prove themselves having lost 2-0 to Besiktas in Istanbul in September.
"We are eager to do better than in the first leg, we do not like to lose twice against the same opponent," said Hasenhuettl.
"Besiktas were the team to beat in our group and we want to prove that we're capable of beating a team like that in the Champions League.
"We're going to give it absolutely everything we've got."