BERLIN, Sept. 19 (Xinhua) -- Two goals from Erling Haaland helped Borussia Dortmund to inflict a resilient Union Berlin its first defeat of the season at the closer of the fifth round in Bundesliga on Sunday.
The "Eisernen" thought they had caught a perfect start on the road but for all that Taiwo Awoniyi's goal was ruled offside in the first minute of the game.
Dortmund then gained the upper hand and broke the deadlock with 10 minutes played after Raphael Guerreiro finished off a combination via Mahmoud Dahoud, beating Berlin goalkeeper Andreas Luthe from 15 meters.
The "BVB" increased the pressure and doubled the advantage following a counterattack as Thomas Meunier's pinpoint cross allowed Haaland to head home a 2-0 lead in the 24th minute.
Union couldn't hold the pace in the first half, and to make things worse Marvin Friedrich cleared Marco Reus dangerous square pass into the wrong goal to make it three for Dortmund in the 52nd minute.
The own goal was a wake-up call for the visitors who suddenly sparked to life as Max Kruse converted a foul play penalty to reduce the arrears to 3-1.
Dortmund ceased its offensive actions and got promptly punished with another goal by Union as Niko Gieselmann's corner kick found Andreas Voglsammer, who nodded home to make it 3-2.
Just when Union was about to take things over, Haaland destroyed all hopes of a comeback as the Norway international beat Luthe to secure the 4-2 win in the 83rd minute.
With the result, Dortmund defended its third spot in the Bundesliga standings while Union Berlin remains on the eighth place.
"We had everything under control and were three goals ahead, but we still allowed the opponents to come back. That is unnecessary. There are still things that we need to improve," Borussia Dortmund head coach Marco Rose said.
"At the end of the day you have to play a perfect game in Dortmund for 90 minutes otherwise you won't reap any points," Union Berlin head coach Urs Fischer said.
Elsewhere, 10-men Bayer Leverkusen edged Stuttgart 3-1 thanks to Robert Andrich, Patrik Schick and Florian Wirtz, and unbeaten Wolfsburg lost its top spot to Bayern Munich after sharing the spoils with winless Eintracht Frankfurt following a 1-1 draw. Enditem