Jens Keller's men could seal a place in the last 16 with a win, but they will be without Marco Hoger, Chinedu Obasi and Kyriakos Papadopoulos through injurySchalke will be looking to bounce back from consecutive 3-0 defeats to Chelsea when they visit Steaua Bucharest on Tuesday.
The Bundesliga side still sit second in Group E of the Champions League, with Basel having squandered two opportunities to climb into the top two with back-to-back 1-1 draws against Steaua, but any more dropped points could seriously hamper Schalke's chances of reaching the knockout stages.
Jens Keller will take confidence, though, from the reverse fixture against the Romanian club, which ended in a 3-0 victory, with Atsuto Uchida, Kevin-Prince Boateng and Julian Draxler netting in the second half.
Steaua currently occupy bottom spot with just two points and two goals to show from the opening four fixtures, so anything other than a win in this match would see them eliminated from the competition.
In contrast to their continental form, Steaua are unbeaten in their domestic campaign, with nine victories and three draws from their 12 ties.
They have not played since November 6 after their last fixture against Universitatea Cluj was postponed to allow players more time to prepare for Romania's World Cup qualifying play-off clash against Greece, which they lost 4-2 on aggregate.
Schalke have won six of their last 10 matches away from home, losing just one, and sit sixth in the German top flight, four points adrift of the Champions League qualifying positions.
Marco Hoger (knee), Chinedu Obasi (tibia) and Kyriakos Papadopoulos (knee) are all set to miss out for Schalke, while Klaas-Jan Huntelaar (knee) is unlikely to return to first-team action until the new year.
Meanwhile, Steaua will be without Lucian Filip, who is sidelined after suffering a broken leg in training last week, and Mihai Pintilii is likely to miss out with a muscle strain.