Union Berlin claimed the first Bundesliga victory in their history as they stunned Borussia Dortmund.
Marius Bulter gave the hosts, who were promoted to the top flight via the play-offs, the lead when he turned home Christopher Trimmel’s corner.
Paco Alcacer equalised for Dortmund from Jadon Sancho’s cross.
Bulter hit a perfectly-placed second from outside the box before Sebastian Andersson capped a fine passing move to seal the famous win.
Bulter’s rise has been dramatic. Last season with Magdeburg was the 26-year-old’s first campaign above the regional fourth division, and it ended in relegation from the second division before he moved to Union on loan.
Dortmund had won their opening two games, with Union Berlin – who lost 4-0 to RB Leipzig on the opening day – picking up one point.