Cologne became the first side to stay undefeated against Bayern Munich in the Bundesliga this season, working hard to come from behind and snatch a 1-1 draw on Saturday.
Cologne is unbeaten in its last 11 games going back to last season, while Bayern dropped points for the first time this season to follow Wednesday's 1-0 defeat at Atletico Madrid in the Champions League.
Anthony Modeste claimed the visitors' equalizer with just under half an hour remaining, time enough for Bayern to twice hit the post in a frenetic finale.
Bayern's Joshua Kimmich continued his remarkable recent form by breaking the deadlock five minutes before the break. The midfielder scored with a diving header to Juan Bernat's cross for his third league goal, and his fifth in six games across all competitions.
Bayern went close again in the second half when Javi Martinez struck the post after a corner, before Modeste stunned the home fans with the equalizer, stretching acrobatically to lift the ball over the despairing Manuel Neuer after Marcel Risse crossed from the right.
Carlo Ancelotti reacted by sending on Arturo Vidal and David Alaba with 20 minutes remaining but it was the visitors who next had the ball in the net through Yuya Osako. The Japan striker was offside however.
Then halftime substitute Thomas Mueller drew a brilliant reflex save from Timo Horn at the other end, the Cologne 'keeper pushing his effort onto the post.
Both sides kept pushing for the winner, with Bernat striking the left post for Bayern before Cologne's Simon Zoller was agonizingly wide of the far post in injury time.
In-form Borussia Dortmund was hoping to take advantage at Bayer Leverkusen later Saturday.
HERTHA BERLIN 2, HAMBURGER SV 0
Markus Gisdol's tenure at Hamburg got off to a bad start in Berlin, where Vedad Ibisevic scored twice to take Hertha provisionally second.
The Bosnian striker stopped Alexander Esswein's deflected effort with his left foot and prodded it home with his right before the half-hour mark, and sealed the win with his fifth goal of the season with 20 minutes remaining.
Hertha 'keeper Rune Jarstein earlier produced an outstanding save to push former Hertha forward Pierre Lasogga's free kick onto the crossbar.
Gisdol took over on Monday from Bruno Labbadia, sacked the day before after Hamburg took just one point from the opening five games. It's now six.
Also, Vincenzo Grifo scored early for Freiburg to beat visiting Eintracht Frankfurt 1-0, Hoffenheim won at Ingolstadt 2-0, and Werder Bremen drew at Darmstadt 2-2.