Bayern Munich's perfect Bundesliga start came to a screeching halt when they drew 1-1 with Cologne but they still protected their three-point lead after rivals Borussia Dortmund lost 2-0 at Bayer Leverkusen.
The Bavarians, who lost at Atletico Madrid in the Champions League in midweek, hit the woodwork three times but failed to make their dominance count, with Cologne protecting their undefeated run.
Bayern, however, stayed three points clear at the top on 16 after a surprisingly toothless Dortmund conceded one goal in each half to slump to their second loss of the season at Leverkusen and drop to third on 12, level with fourth-placed Cologne.
"We have not been good in two games but I am confident," Bayern coach Carlo Ancelotti told reporters.
"We started the game well, dominated but in the second half Cologne improved."
"We could have won that game but Cologne also had chances to win it. We can be disappointed but we should not be worried."
The hosts struggled against the hard-working Cologne defenders for 40 minute before Joshua Kimmich finally broke the deadlock, diving to head in a beautiful Juan Bernat cross for the lead.
Thomas Mueller came close to adding another goal four minutes after the restart as did Robert Lewandowski, with Bayern keeping up the pressure and looking to kill off the game.
But it was Cologne who scored when striker Anthony Modeste timed his run to perfection.
Hertha Berlin climbed to second spot on 13 points, after easing past Hamburg SV 2-0 with two goals from Vedad Ibisevic, who became a father late on Friday.
Dortmund were a shadow of their attacking self as mercurial Leverkusen took a 10th-minute lead through Admir Mehmedi's header.
Mexican striker Javier Hernandez scored his fifth goal in a week when he slotted in a Hakan Calhanoglou pass in the 79th to dash any hopes of a Dortmund comeback and lift his team to seventh place.