Dortmund boss Jurgen Klopp said his side's football was "pointless" after they fell to their fifth defeat of the season.
Mario Gotze and Philipp Lahm hit braces as Bundesliga leaders Bayern Munich romped to a 6-0 victory over Werder Bremen.
Cologne piled further misery on Borussia Dortmund with a 2-1 win which leaves Jurgen Klopp's men in 14th place.
Sir Alex Ferguson believes Manchester United’s signing of Juan Mata ended any hope Shinji Kagawa had of succeeding.
Borussia Dortmund coach Jurgen Klopp said his side had hit "rock bottom" after Saturday's 1-0 defeat at home to Hamburg.
Hamburg picked up their first Bundesliga win to pile misery on Borussia Dortmund, while Bayern Munich thrashed Hannover.
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