1. FC Union Berlin were beaten 0-2 at the Signal Iduna Park against Borussia Dortmund.

A controversial first-half goal from Marco Reus and an 88th-minute goal from Raphael Guerreiro secured the three points for the home team. 

Borussia Dortmund: Hitz; Piszczek, Akanji, Hummels, Guerreiro; Reyna (Brandt 75), Bellingham (Renier 90), Can (Dahoud 58), Reus, Hazard (Sancho 58); Haaland

1. FC Union Berlin: Luthe, Trimmel, Knoche (Schlotterbeck 72), Friedrich, Lenz; Prömel (Gentner 80), Andrich; Kruse (Teuchert 72), Endo (Bülter 57), Ingvartsen; Musa (Pohjanpalo 72)

Marcus Ingvartsen and Keita Endo were introduced to the starting eleven for 1. FC Union Berlin, four days after the 2-1 win over VfB Stuttgart. It took the Danish international 12 seconds to put Borussia Dortmund on the back foot, striking from distance and hitting the crossbar. Union’s start was proactive and ambitious, with Endo breaking into good positions from the left-hand side. Edin Terzic’s side included a number of dangerous players in forward areas, from Erling Haaland to Marco Reus and Giovanni Reyna. Goalkeeper Andreas Luthe was busy in the opening 20 minutes and he kept out from Haaland as the Norwegian looked set to score. On 25 minutes, referee Daniel Schlager was at the centre of controversy, as well as, his video assistant colleague Eduard Beitinger in Cologne. Reus went through on goal and hit the deck under minimal contact, but the decision to award a penalty kick stood in the end. Luthe won the battle against Haaland from 12 yards but pressure from the striker led to the ball dropping to Reus for the opening goal. Four minutes later, Petar Musa threatened in behind the Dortmund defence but the Croatian U21 international was flagged for offside after an excellent through ball from Ingvartsen. In the Champions League, Borussia Dortmund were narrowly edged out by Premier League league-leaders Manchester City, and at times, that quality was on show at the Signal Iduna Park. But a mixture of Union’s organisation at the back and smart possession managed to hold the scoreline to 1-0 at the interval.

Borussia Dortmund may feel they should have put the game beyond doubt a few minutes into the second half at the Signal Iduna Park. Reyna was through on Luthe from the right corner of the box and the youngster's chip was inches wide of the post. As Borussia Dortmund turned to Jadon Sancho and Mahmoud Dahoud, Union introduced Marius Bülter in place of Endo as Fischer's side looked for fresh pace and legs in attack. American international Reyna came close again on 64 minutes after a run from substitute Sancho, but Christopher Lenz was well positioned on the line to clear. Union found themselves cursing their luck from range in the 65th minute as Max Kruse's wonderfully-struck set-piece came back off the crossbar after beating Marwin Hitz in the Borussia Dortmund goal. A few milimetres lower, as with Ingvartsen's shot, and Union would have found themselves on level terms. With the Bundesliga in an English Week, Fischer tweaked with his side on 72 minutes in order to keep energy in the tank ahead of Saturday's home match against Werder Bremen. Robin Knoche was replaced at centre back by Nico Schlotterbeck, Max Kruse came off for Cedric Teuchert and Joel Pohjanpalo took the spot of Musa up front. Christian Gentner, who started the win over Stuttgart at the weekend, was the final change of the five as Grischa Prömel made way. Capping off an excellent performance, Luthe kept out Haaland again as the top scorer at Borussia Dortmund drove into the box but couldn't find a route past the Union goalkeeper. But with two minutes left on the clock, Guerreiro rounded off the scoring with a finish on the break.

Union's demanding schedule this week will end at home to Werder Bremen on Saturday afternoon at 15:30 CET. In line with the current infection protection regulations, the match at the Stadion An der Alten Försterei will take place behind closed doors.