Borussia Dortmund ended Bayern Munich's unbeaten start to the league campaign with a 1-0 Der Klassiker victory courtesy of Pierre-Emerick Aubameyang's first-half goal.
The hosts, who had not triumphed over their fierce rivals in the league since 2014, ignited their Bundesliga title hopes with a gritty display at Signal Iduna Park, where they spent long spells on the back foot en route to a 27th home league match without defeat.
Thomas Tuchel's men rode their luck at times and were ultimately indebted to Aubameyang's close-range 11th-minute finish, which brought them to within three points of their visitors.
It is RB Leipzig – 3-2 winners over Bayer Leverkusen on Friday – who lead the way, but Bayern will wonder how they did not at least claim a draw on Saturday.
Franck Ribery had a goal ruled out for offside and Xabi Alonso struck the woodwork for Carlo Ancelotti's side, who almost conceded a second when Aubameyang proved uncharacteristically profligate after finding himself one-on-one with Manuel Neuer.
It was Aubameyang, who scored four in the 5-2 win over Hamburg before the international break, who broke the deadlock following a frenetic start to the match.
With the hosts applying pressure, Bayern failed to clear their lines and ex-Allianz Arena favourite Mario Gotze got past former team-mate Mats Hummels to pick out Aubameyang, who slide in to poke home his 12th league goal of the season.
The visitors caused panic in the Dortmund box just before the break, with Lewandowski lurking as Sokratis Papastathopoulos made a telling interception from Ribery's cross.
But Ancelotti's side were almost caught cold at the start of the second half as Aubameyang nodded Marcel Schmelzer's delivery over the target from eight yards.
Aubameyang should have sealed it in the 70th minute, racing clear on goal, only to shoot tamely at an alert Neuer, who turned it behind for a corner.
