Cologne came from behind to draw 1-1 against Werder Bremen - their seventh home stalemate of the season.
Bayern Munich continued their free-scoring form with a 4-0 win at Werder Bremen on Saturday.
Werder Bremen got back to winning ways after back-to-back defeats with a 1-0 win at relegation-threatened Freiburg.
Wolfsburg needed a second-half fightback to win 5-3 at Werder Bremen, while Borussia Monchengladbach beat Paderborn 2-0.
Wolfsburg refused to lie down as they inflicted the first defeat of the 2015 on Werder Bremen with a stunning 5-3 win.
Security will be tightened around Werder Bremen's game with Wolfsburg after police warned of a possible terrorist attack.
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