Before the emotional reunion with Borussia Mönchengladbach, coach Marco Rose and his new club Borussia Dortmund crowned a perfect week with the third win within eight days.
At 4: 2 (2: 0) on Sunday, BVB initially showed the unbeaten 1. FC Union Berlin the limits, but made it unnecessarily exciting in the end.
Again, Dortmund caught against long harmless goals from Berlin: Max Kruse with a penalty kick (57th minute) and Andreas Voglsammer (81st), who came on for him, were successful for Union.
Raphaël Guerreiro with a volley dream goal (10th) and of course Torgarant and Bundesliga top scorer Erling Haaland with his sixth and seventh goals in the fifth game of the season (24/83) scored the goals for BVB.
In addition, Union captain Marvin Friedrich underwent an own goal (52nd).
With twelve points, the Westphalia remain just one point behind Bayern Munich.
In the coming week, Rose faces the emotionally charged prestige duel in Gladbach with BVB, where the Dortmund coach has to expect fierce fan reactions after his move in the summer.
With the Westphalian Borussia, things are currently going very well for Rose.
The deserved victory on Sunday was the seventh home game won in a row and the third victory in a week after the 4: 3 spectacle in Leverkusen and the 2: 1 in the Champions League at Besiktas Istanbul.
You can rely in particular on the Haaland gate machine, which is now also successful on a head. In the past few days, Rose had identified room for improvement in this regard in the 21-year-old. His 2-0 goal was only his fourth header in a total of 47 league goals, but Haaland had already been successful with a header in Leverkusen. The Norwegian also made the decision in the final phase. Previously, Guerreiro had put Dortmund in the lead in the strong initial phase with a dream goal volley into the far corner.
For Union there was nothing to be gained in the third game in Dortmund since the promotion to the Bundesliga.
The team of coach Urs Fischer ran behind early on and allowed itself to be pushed far on the defensive.
Three days after the 1: 3 in the Conference League at Slavia Prague, the Köpenickers didn't look as fresh as Dortmund, which had already played against Turkish champions Besiktas on Wednesday.
In Sunday's constitution, there was no question of ending the club's current negative record of eight away games in a row without a win.
It fit into the picture that Friedrich stumbled into his own net with an energetic advance from BVB captain Marco Reus - this was the supposed preliminary decision.
Fischer tried again with a double change: Cedric Teuchert and Kevin Behrens replaced the disappointing Taiwo Awoniyi and Levin Öztunali, who immediately afterwards took the penalty in a duel with Axel Witsel. Kruse routinely brought Union up again - the 33-year-old safely converted the 20th of his 21 penalty kicks in the Bundesliga. The standard weakness of BVB actually brought Union dangerous again. Voglsammer headed a 2: 3 after a corner. Just two minutes later, goalgetter Haaland saved the Dortmund victory with a spectacular lift, and Reus hit the post with a free kick (86th).