Heidenheim's on-loan midfielder Eren Dinkci scored twice in a 4-2 win against his parent club Werder Bremen on Sunday to give the promoted side their first ever Bundesliga victory.
Bremen-born Dinkci, who joined Heidenheim on loan from Werder in July, scored either side of half time as the Bundesliga newcomers prevailed in one of two six-goal thrillers in the Bundesliga on Sunday.
In Sunday's late game, another promoted side Darmstadt threw away a three-goal lead to draw 3-3 with Borussia Moenchengladbach.
"It's a great feeling. My first brace in the Bundesliga, and it comes against Bremen of all clubs. My whole family is here today, so it doesn't get much better than this," Dinkci told DAZN after Heidenheim's win.
The club's first top-flight win came on a weekend when coach Frank Schmidt celebrated 16 years in the dugout, making him the longest-serving coach in German league history.
Schmidt took over Heidenheim in the fifth tier back in 2007, but he dismissed talk of a fairytale on Sunday.
"There was nothing cheesy about today's win. It was just an awesome game of football," he said.
Tim Kleindienst gave Heidenheim an early lead from the penalty spot after Bremen's Anthony Jung threw an elbow at the ball while defending a free-kick.
The home side then doubled their advantage on the stroke of half-time through Dinkci, who refused to celebrate after smashing the ball past former teammate Jiri Pavlenka in the Bremen goal.
The visitors looked down and out at half-time, but were given a route back by an Omar Traore handball.
Marvin Duksch hit the resulting penalty straight at Heidenheim goalkeeper Kevin Mueller before nodding in the rebound to make it 2-1.
Bremen missed a good chance to equalise through Romano Schmid before Mitchell Weiser pulled them level with a well-placed header on 64 minutes.
Dinkci restored the lead four minutes later, slotting the ball into the bottom corner from the edge of the area after a cross from Jan-Niklas Beste.
Beste, who spent a year at Bremen's reserves in 2018/19, rifled in a fourth a few minutes later to seal the win.
- Gladbach miracle -
Later on Sunday, Borussia Moenchengladbach staged a miraculous comeback in Darmstadt, in part thanks to a controversial red card.
Darmstadt started the game bottom of the table, but exploded into the first half with two goals in the first ten minutes.
Marvin Mehlem picked up a looping long ball to slot home the first. Matej Maglica doubled the lead with a header two minutes later.
Tim Skarke blasted in a third on the half-volley just after the half-hour, putting Darmstadt on course for a first win of the season.
The game turned early in the second half when Maglica was sent off after appearing to brush the ball with his hand in the box.
"We were lucky the decision went our way because it gave us a chance to get back in the game," said Gladbach midfielder Julian Weigl after the whistle.
Tomas Cvancara missed the penalty, but US international Jordan Siebatcheu Pefok pulled a goal back for Gladbach a few minutes later.
Florian Neuhaus added a second from close range on 73 minutes, before Cvancara atoned with a brilliant long-range equaliser.