Union shock Dortmund 3-1 for maiden Bundesliga win

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 1. FC Union Berlin's Sebastian Andersson scores their third goal REUTERS/Annegret Hilse

BERLIN (Reuters) - Promoted Union Berlin stunned title contenders Borussia Dortmund 3-1 on Saturday to earn their first ever Bundesliga victory that left their opponents three points off the top.

Dortmund fell behind for the third straight league game but their in-form frontline that had scored eight goals in the previous two matches were largely toothless this time.

Marius Buelter gave the hosts a shock lead in the 22nd minute, but their joy was short-lived with Dortmund forward Paco Alcacer stabbing in an equaliser three minutes later to continue his run of scoring in every Dortmund game so far.

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 Borussia Dortmund's Manuel Akanji heads at goal REUTERS/Annegret Hilse

Yet instead of turning the game around as they had done in previous weeks, Dortmund showed little attacking appetite against a disciplined Union side and soon conceded again.

Buelter slotted in on the rebound after keeper Roman Buerki had done well to stop a shot and the goal exposed Dortmund's defensive weakness so far this season.

Sebastian Andersson then completed a fine passing move in the 75th to score their third as the Alte Foersterei stadium erupted in song and fans lit flares.

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 1. FC Union Berlin's Anthony Ujah in action with Borussia Dortmund's Julian Weigl REUTERS/Annegret Hilse

"Obviously we are very disappointed," said Dortmund's Julian Brandt. "We have to learn from this. We are responsible for the way we play. We should have avoided falling behind in the first place."

The Ruhr valley club's first loss of the season leaves them on six points in fifth place, three behind leaders RB Leipzig, who are on nine after their 3-1 win over Borussia Moenchengladbach. Union are on four points.

Champions Bayern Munich demolished Mainz 05 6-1 to climb into second place on seven points.

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 Borussia Dortmund's Julian Weigl in action with 1. FC Union Berlin's Manuel Schmiedebach REUTERS/Annegret Hilse

(Reporting by Karolos Grohmann; Editing by Toby Davis)

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 Borussia Dortmund's Paco Alcacer scores their first goal REUTERS/Annegret Hilse

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 Borussia Dortmund's Paco Alcacer scores their first goal REUTERS/Annegret Hilse

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 1. FC Union Berlin's Marius Bulter scores their second goal REUTERS/Annegret Hilse

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 Borussia Dortmund's Mats Hummels in action with 1. FC Union Berlin's Marius Bulter REUTERS/Annegret Hilse

Soccer Football - Bundesliga - 1. FC Union Berlin v Borussia Dortmund - Stadion An der Alten Forsterei, Berlin, Germany - August 31, 2019 1. FC Union Berlin's Neven Subotic with Borussia Dortmund's Jacob Bruun Larsen after the match REUTERS/Annegret Hilse