Dortmund have climbed the table to second place after rediscovering their championship-winning form with five wins and a draw in their last six league games.
The reason for Dortmund's rich vein of form was that the players were hungrier for the ball, coach Jurgen Klopp told a group of amateur league coaches this week.
"When we started studying our system it was more a case of a Swan Lake. Now we always want to grab the ball like piranhas," Klopp said.
"We just have to show no fear," said Germany defender Mats Hummels. "We have to push our own game through and then Bayern will not be invincible anymore."
Dortmund could be without defender Marcel Schmelzer, who missed Germany's friendlies this week with a muscle injury.
"Dortmund are the toughest of all our rivals," said midfielder Bastian Schweinsteiger, who has been ruled out for the rest of the year with a shoulder injury.
"It will be a tight game but I am sure that we will throw everything we have into this game and win, because then we will have taken a huge step forward."
Bayern are also hoping they will make amends for last season's 3-1 defeat in Munich that all but sealed Dortmund's title.
"A lot has changed since then," Schweinsteiger told reporters after watching a Bayern Munich basketball game late on Wednesday. "We have more quality this season and we are more compact than in the past few seasons."
