Borussia Dortmund missed the chance to move within a point of Bayern Munich in the Bundesliga table as they were beaten 2-0 by Bayer Leverkusen at the BayArena.
Carlo Ancelotti's men dropped two points against Cologne earlier on Saturday, but Dortmund failed to take advantage and lost further ground on the defending champions.
Admir Mehmedi handed Leverkusen an early lead when he headed home a corner from Hakan Calhanoglu.
And Thomas Tuchel's men were unable to find a way back, Javier Hernandez putting the match to bed 11 minutes from time after a quick counter-attack.
The victory marks Leverkusen's first home league win over Dortmund since May 2007, having drawn five and lost four in the fixture since then.
Dortmund, meanwhile, drop to third in the table following their second defeat of the season having taken 12 points from six games and are four points adrift of leaders Bayern.
Tuchel started without Mario Gotze in attack, with Christian Pulisic named in the starting XI instead, while Marcel Schmelzer started from the bench as well.
Leverkusen began strongly and went 1-0 up after just 10 minutes through Mehmedi. Dortmund goalkeeper Roman Burki did well to keep out Javier Hernandez's header after a cross from the left, but the former Freiburg man was beaten from the resulting set piece.
Calhanoglu curled in a sublime corner for Mehmedi and the attacker rose higher than Julian Weigl before heading the ball into the top-left corner past the helpless Burki.
Dortmund immediately went in search of an equaliser and Pierre-Emerick Aubameyang had a fine chance to level the scoring. The Gabon international latched on to Lukasz Piszczek's pass with a clever run in behind the defence, only to aim his low shot straight at shot stopper Bernd Leno.
The hosts went close to doubling their lead on the half-hour mark when ex-Dortmund midfielder Kevin Kampl tried his luck against his former team with a powerful shot from the edge of the box after some sloppy play from Raphael Guerreiro, the Slovenia international's effort going just wide.
Leverkusen remained in charge after the break and had chances to net a second via Wendell and Kampl, with the Brazilian's shot from inside the area narrowly missing the target, before the latter forced Burki into a fine save.
Dortmund struggled to break down Leverkusen at the other end but they almost restored parity with 17 minutes left. Aubameyang outmuscled Omer Toprak and Jonathan Tah before firing a low shot at Leno, with the goalkeeper only just able to prevent the equaliser.
Aubameyang's failure to beat Leno proved costly just minutes later when Hernandez sealed the points after a rapid break. Kevin Volland set up Calhanoglu down the left, and the Turkey international duly found Hernandez, who had no trouble sliding the ball past Burki.
Dortmund did have the ball in the net through Aubameyang late on, only to be denied by the offside flag on a frustrating day for Tuchel and his side.