A largely even first half in Stuttgart was punctuated by a horrific error from Alexander Nubel, whose flapping attempt at a save led to the opening goal.
Danilho Doekhi was the man who rose highest inside the penalty area to meet Andras Schafer’s chipped cross, but much to the frustration of the 60,000 or so inside the Neckarstadion, the Stuttgart goalkeeper’s wrists were weak, with the ball sneaking just across the goal line.
A gift for Union, given Stuttgart had come closest to scoring before going behind, with Ermedin Demirovic skewing an effort just over the crossbar.
One became two pretty shortly after the break, with Robert Skov’s cross-cum-shot sneaking in at the far post.
Rani Khedira, who previously enjoyed a stint with Stuttgart, had initially claimed the goal, but replays showed the German didn’t touch the ball, meaning Skov was credited with the strike, his first for Die Eisernen since his arrival in the summer.
Sitting on a two-goal lead, not even the most pessimistic of Union fans would have predicted what followed.
The hosts’ comeback began almost immediately when Nick Woltemade rounded goalkeeper Frederik Ronnow prior to tapping into an empty net, and the substitute restored parity eight minutes later, this time tucking a tidy finish beyond Ronnow and justifying manager Sebastian Hoeness’ half-time switch.
The turnaround was complete midway through the second half, but it was a goal of Union’s own doing as Ronnow passed the ball straight to Stuttgart’s Atakan Karazor, allowing the captain to fire home from 12 yards out.
Die Schwaben were subsequently able to see out the remainder of the match to move into the Bundesliga's European qualification spots, albeit with the rest of the German top flight still to play this weekend.
Union, meanwhile, remain six points ahead of the bottom three in 11th and are now winless in their past seven games in all competitions.
Flashscore Man of the Match: Nick Woltemade (Stuttgart)