Borussia Dortmund was in the dock away from Augsburg and was down 3-1 when they replaced the new acquisition Erling Håland.
The Norwegian striker, who joined from RB Salzburg, thanked for the confidence - and scored three goals in 20 minutes.
First he got into the penalty area, finished with a touch and picked up the ball from the nets to quickly start the game.
Then Håland had only been on the pitch for three minutes. Then the score was 2-3. Then the shooter king wasn't done.
With 70 minutes played, he shaved 3-4 in the open cage. In between, the weatherman Jadon Sancho had managed to get to 3-3.
Nine minutes later, Håland went deep, made room for his left and rolled in the final score 5-3 in the distance.
Dortmund has thus continued to hang on series leader RB Leipzig, who has a lead of four points.
For 19-year-old Håland, who was chased by several major clubs before choosing Dortmund in December, the debut was spotless.