"On the one hand, it is still pre-season, but on the other hand, it does show us where we are and it is a welcome opportunity for us to measure up at a very high level," said Bayern's coach Jupp Heynckes.
"Both sides are on a par and it will be decided by nuances - the form on the day."
Bayern have lost their last five encounters with Dortmund - a new club record of consecutive defeats to one single opponent.
"We have got to come into the game with a clean slate," Heynckes said on his club's website. "We cannot think about the past.
"Only then will we be able to play much better and much more successful football."
The two best teams in German football will not be able to field their best players, though.
Bayern's vice-captain Bastian Schweinsteiger returned to training today and is unlikely to be fit while Mario Gomez is out after undergoing ankle surgery and Claudio Pizarro remains a doubt.
Sven Bender underwent groin surgery yesterday and misses out along with Dortmund's captain Sebastian Kehl, but Mario Gotze is out after recovering from an eye infection.
New Dortmund arrival Marco Reus is set to take replace Shinji Kagawa, who has joined Manchester United, while Emre Can is set for his Bayern debut at left full-back given the absences of Diego Contento and David Alaba.