Dortmund's performances in the group stage of the Champions League have turned them into serious candidates European football's biggest prize, but that makes the challenge of beating them even more attractive to Mainz coach Thomas Tuchel.
Mainz play host to the reigning champions this weekend and Tuchel said: "I certainly do believe that there is a huge gulf between the two clubs, for example in terms of individual quality and the financial means, but it is an art to overcome this gap over the space of 90 minutes.
"We too have been playing a pretty decent season. We just need to be courageous and confident."
Dortmund's 4-1 win over Ajax in midweek does not make the challenge any different, according to Tuchel.
"It did not make me bite my fingernails - I always knew what we will be up against on Saturday," he said.
Dortmund coach Jurgen Klopp, who spent 18 years as a player and coach of Mainz before moving to Dortmund, has a big task of his own in turning his side's attention to the Bundesliga after another successful night in Europe.
"It's never easy to get three points in Mainz," said Klopp, whose side lost their first game in almost a year immediately after their opening Champions League game this season and only drew after their second European encounter.
Sven Bender may miss out after breaking his nose against Ajax, although he could be able to play with a mask.