Bayern has yet to drop any points after seven games while Dortmund slipped to draws against Hoffenheim and then Darmstadt after starting with five wins.
The team is already four points behind. Seven, Bayern wins on Sunday, would seem an insurmountable gap baring an extraordinary collapse from the defending champions.
Here are some things to know about this weekend's matches:
Few believe that any side but Dortmund can challenge Bayern for the title this season.
Wolfsburg, last year's runner-up, is already nine points behind. Third-place finisher Borussia Moenchengladbach is 15 behind and fourth-place Bayer Leverkusen is also nine behind.
Schalke, currently third and five points behind Bayern, is undergoing a period of change under new coach Andre Breitenreiter, who is trying to counter burgeoning expectations of his talented but young side.
Under new coach Thomas Tuchel, Dortmund forgot last season's travails (the club was last in February) and bounced back with a club-record start to 2015-16.
The draw at Hoffenheim was the first blow after 11 wins in all competitions, before Darmstadt scored in the final minute last Sunday to deliver another.
Bayern could arguably deliver the final blow to Dortmund's title chances on Sunday.
Bayern is on a high after making the best start any side has ever made to the Bundesliga. No side claimed as many points (21) or had a better goal difference (plus-20) at this stage of the campaign.
However, only one team of the four to have won their opening seven games went on to win the league.
Bayern has also made its best ever start to the Champions League after 3-0 and 5-0 wins over Olympiakos and Dinamo Zagreb, respectively.
Former Dortmund striker Robert Lewandowski is in the form of his life, with 10 goals in three games, including the five he scored in nine minutes against Wolfsburg and his hat trick against Dinamo.
"He bought my run," joked Thomas Mueller, who started the season with eight goals in five games across all competitions before Lewandowski took over.
With an eye on Sunday's game, Dortmund was resting key players against Greek side PAOK in the Europa League on Thursday.
Defenders Mats Hummels and Sokratis Papastathopoulos, midfielders Shinji Kagawa and Ilkay Gundogan, as well as forward Pierre-Emerick Aubameyang were all left out of the trip to Thessaloniki.
With nine goals in seven Bundesliga games, Aubameyang is just one behind Lewandowski.
"We have to keep an eye on the demands being placed on the players," Tuchel said.
Bayern will have had two days extra rest after its win over Zagreb on Tuesday. The players were treated to some of the annual Oktoberfest celebrations on Wednesday.
Schalke will be hoping to take advantage of any further slip-ups from rival Dortmund.
Under Andre Breitenreiter, the side has made its best start to the league in 44 years, and it appears to be showing a maturity - an ability to grind out results - that was lacking in previous seasons.
Nineteen-year-old Leroy Sane is the latest exciting player to emerge from the club's youth setup, scoring in three consecutive league games to hamper Breitenreiter's efforts to keep expectations low.
Schalke hosts Cologne on Sunday, when a win would take the side second before "der Klassiker" gets underway.
CHAMPIONS LEAGUE DUEL
Borussia Moenchengladbach hosts Wolfsburg on Saturday with both sides hoping to bounce back from defeats to Manchester sides in the Champions League on Wednesday.
Andre Schubert's two-game winning start as interim 'Gladbach coach was ended by Man City, while Dieter Hecking's Wolfsburg lost by the same 2-1 score to Man United.
Both sides are still finding their feet in the Bundesliga after lackluster starts to the season, particularly 'Gladbach, which started with five losses before Schubert's predecessor, Lucien Favre, resigned.