Heidenheim striker Tim Kleindienst scored from the centre circle as the promoted Bundesliga side stunned high-flying neighbours Stuttgart with a 2-0 win on Sunday.
Kleindienst's brilliant long-range strike in injury time handed the underdogs a famous win as the two south-western clubs met for the first time in Germany's top flight.
Stuttgart, who had been the surprise package of this season with seven wins from their first eight games, have now lost two regional derbies in a row after defeat to Hoffenheim last weekend.
They remain in third after Sunday's loss, but have slipped seven points behind league leaders Bayer Leverkusen and five behind champions Bayern Munich in second.
Heidenheim had 13 shots on goal and hit the woodwork twice in the first half, while Stuttgart almost took the lead when Angelo Stiller grazed the bar with an elegant free-kick.
The visitors should have taken the lead when Waldemar Anton was fouled in the box early in the second half, but Silas Katompa Mvumpa sent the ball into orbit from the penalty spot.
Yet it was Heidenheim who broke the deadlock when Schoeppner charged into the box at a corner to power home a header on 70 minutes.
As Stuttgart increased the pressure late on, Luca Raimund hit the bar and Jamie Leweling had a header cleared off the line.
Yet Kleindienst pounced on a defensive error late on, lobbing goalkeeper Alexander Nuebel from just inside the Stuttgart half to seal the win.
- Paredes scores for Bremen -
In Sunday's early game, US international Kevin Paredes scored a rare Bundesliga goal as Wolfsburg were held 2-2 at home by Werder Bremen.
Wolfsburg midfielder Paredes, 20, found the net for the first time this season as Niko Kovac's side came from behind to end a run of three straight defeats in the league.
Bremen made a dream start when Marvin Ducksch curled a direct free-kick in off the post on seven minutes.
Vaclav Cerny levelled the scores against the run of play shortly before half time, nutmegging Bremen keeper Michael Zetterer with a sharp finish.
Paredes put Wolfsburg 2-1 up from close range after the break, doing well to stay on his feet and stab home Lovro Majer's backheeled assist.
It was only Paredes' second Bundesliga goal in 31 league games for Wolfsburg, and his first this season.
The American's joy was short-lived, as Bremen's Rafael Borre equalised a few minutes later with a thundering header into the bottom corner.
Wolfsburg's Maxence Lacroix was sent off late on for a second yellow card, but the hosts held on with ten men.
"Given the quality of the chances we had today, we could have won the game," said Bremen's Ducksch.
The draw, which was the first of the season for both sides, left Wolfsburg in ninth and Bremen in 12th.