Hertha Berlin have announced that United States international John Brooks will be out "for the time being" with a hip injury.
Bayern struggled to move on from Madrid, stumbling to a 2-2 draw against Mainz at the weekend. Dortmund in the cup can prove salvation.
Hertha Berlin have said they do not believe Liverpool will get a work permit for Allan as they prepare to open talks to extend his loan.
Coach Thomas Tuchel had suggested Sahin could miss the rest of the campaign.
U.S. international was given a score of six by kicker -- the lowest in the German football magazine's ratings system.
Bayern Munich captain Philipp Lahm has said now is not the time to be "sentimental" but wants to crown his playing career with a seventh DFB Pokal.