Bayern Munich lost their first game of the season on Saturday as Borussia Dortmund's 1-0 win at the Westfalenstadion left top-flight new boys Leipzig top of the table.
Pierre-Emerick Aubameyang's 11th-minute goal proved to be the difference between the two heavyweights in Der Klassiker as Dortmund moved to within three points of second-placed Bayern, who trail Leipzig by three points.
Bayern's defeat enabled Cologne also to close to within three points of the Bavarians thanks to their 2-1 win at local rivals Borussia Monchengladbach.
Lars Stindl put Gladbach in front, but it was not enough to lift the pressure on coach Andre Schubert as Anthony Modeste and Marcel Risse earned the visitors all three points.
Gladbach have now gone six games without a win and slumped into the bottom half of the Bundesliga.
Hertha Berlin are also just three points behind Bayern after they picked up a point in Augsburg, although they were frustrated in a goalless draw.
Ingolstadt marked Maik Walpurgis first match in charge with their first victory of the season, a 1-0 win at Darmstadt, thanks to a Moritz Hartmann goal.
Mainz beat Freiburg 4-2, with Yunus Malli instrumental with a goal and two assists.
Niko Bungert headed in Malli's corner in the 15th minute and Malli converted a penalty five minutes later after Jhon Cordoba had been fouled by Caglar Soyuncu. Malli had to take his penalty twice as the referee saw too much encroaching on his first attempt.
Vincenzo Grifo reduced the arrears midway through the second half, but Stefan Bell restored Mainz's two-goal cushion with another header from a Malli corner.
Nils Petersen gave Freiburg hope heading into the final five minutes, but Karim Onisiwo added Mainz's fourth with the final kick of the game.
Schalke extended their unbeaten run to six games with a 1-0 win in Wolfsburg.
Leon Goretzka scored the only goal of the game as Valerien Ismael's first game as Wolfsburg's permanent boss resulted in their fourth home defeat of the season.