Four straight league wins had helped Dortmund into a healthy position, well clear of the chasing pack, albeit with an optimistic title charge now appearing beyond them.
As such, the onus was on the away side, who still harboured hopes of a top-four finish after what has been a rather underwhelming title defence.
A slow start featured no efforts on goal from either side, but BVB could have taken the lead with their first effort on target as Loic Bade headed Daniel Svensson’s strike off the line.
Three of Die Werkself’s last four Bundesliga encounters had seen over 5.5 goals, yet that trend appeared unlikely to continue as the sides were restricted to attempts from range.
Nonetheless, one of those speculative strikes proved to be the opener, with Andrich seizing possession and driving a low shot inside the far post to put the visitors ahead before half-time.
A short period of Dortmund pressure after the break soon gave way to a midfield battle, prompting both managers to turn to their benches in search of inspiration, with substitute Patrik Schick then firing a close-range shot from a tight angle straight at Gregor Kobel.
Leverkusen were the side on top as the game drifted towards full-time, with an unusually flat Signal Iduna Park failing to spark Die Schwarzgelben into life.
With time running out, a smart turn allowed Serhou Guirassy to get a shot off from inside the box, but he rifled it onto the underside of the crossbar, shortly before Julian Brandt sent a low effort narrowly wide deep into stoppage time, sealing the result.
Although disappointing, a first loss to a side starting the day outside the top five this season (W17, D4) does little to affect Dortmund’s position, with an eight-point buffer almost certainly enough to see them through to the end of the campaign in second.
However, the result is far from inconsequential for Leverkusen, who move up to fifth and are now just one point off the top four thanks to their first pair of back-to-back league wins since January.
Flashscore Man of the Match: Loic Bade (Bayer Leverkusen)
