Jürgen Klopp's side ended last season ten points clear of third-placed Bayern, but they already lie six points behind the Bavarians, and three behind Bremen, with just eight games of this campaign played.
For Klopp, this weekend's brief is simple: to compose a team "which is capable of bringing the points back from Bremen."
Dortmund have a busy few weeks ahead of them, including a vital Champions League double-header against Olympiakos.
They signed off before the international break with a confidence-boosting 4-0 win over Augsburg.
Polish striker Robert Lewandowski scored a hat-trick in that rout but his place in the starting line-up at the Weserstadion is under threat from Lucas Barrios, the Paraguayan striker who is fit again after a two-month injury lay-off.
Dortmund's teenage midfielder Mario Götze, who scored the fourth goal against Augsburg, was inspirational in Germany's 3-1 win over Turkey in their final Euro 2012 qualifier in midweek.
That match was also remarkable for the fact Bayern trio Mario Gomez, Thomas Müller and Bastian Schweinsteiger all scored a goal apiece as Germany claimed their ninth win in nine qualifiers before making it a perfect ten against Belgium on Tuesday.
Bayern host Hertha Berlin on Saturday looking to extend an impressive start which has seen them go unbeaten since the opening day of the season, with goalkeeper Manuel Neuer conceding only one goal, against the 21 they've scored.
Fans of Hertha, however, will be praying for a shock. The newly-promoted capital club have already stunned Dortmund and routed Cologne 3-0 with a young side under the coaching leadership of former Bayern player Markus Babbel.
"We've got nothing to lose. And no one is unbeatable," Babbel told AFP. From afar, it seems the only problems affecting Bayern are coming off the field.
In midweek French midfield star Franck Ribery launched a fresh bid to try and ban an unauthorised biography titled "The Hidden Face of Franck Ribery," claiming the book's publishers and authors divulged confidential information relating to an ongoing judicial investigation into his alleged involvement in an under-age call-girl scandal.
Hertha's challenge could be boosted by "all the little tricks" defender Christian Lell says he knows about Ribery, with whom he played at Bayern until last season.
Following a 3-2 reverse to Hannover, Thomas Schaaf's Werder will be hoping their unbeaten form at home holds out against Dortmund.
While their defence has conceded an above-average 10 goals in eight matches so far, 34-year-old Peruvian striker Claudio Pizarro has been showing that age is no concern: since returning from injury, he has scored six times in the league for Werder.
Elsewhere Bayer Leverkusen, who sit ninth, travel to Mönchengladbach, whose third place in the league is down largely to a miserly defence which has conceded only four times so far.
Spanish legend Raul, as well as Dutchman Klaas-Jan Huntelaar, will be looking to fire for fourth-placed Schalke following his recovery from tendinitis when they host 16th placed Kaiserslautern.
On Sunday, bottom of the table Hamburg play their first game under new coach Thorsten Fink when they go to Freiburg.
Werder Bremen v Borussia Dortmund
Bayern Munich v Hertha Berlin, Mainz v Augsburg, Stuttgart v Hoffenheim, Wolfsburg v Nuremberg, Mönchengladbach v Bayer Leverkusen, Schalke 04 v Kaiserslautern
Freiburg v Hamburg, Cologne v Hannover