Marco Reus delivered a damning indictment of a "completely stupid" Borussia Dortmund performance following Saturday's humbling 3-1 defeat at the hands of promoted Union Berlin.
Marius Bulter's brace guided the capital club to their maiden Bundesliga victory and ended Dortmund's perfect start to the season.
Last season's runners-up appeared to have atoned for a poor start when Paco Alcacer cancelled out Bulter's opener but the Union winger added a second after the interval before Sebastian Andersson sealed the upset in the 75th minute.
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Lucien Favre blamed a lack of patience for his team's demise but captain Reus was far more scathing.