Cologne won promotion back to the Bundesliga after two seasons in the second division with a 2-0 home victory over direct rivals Mainz yesterday.
Borussia M'gladbach booked their place back in the Bundesliga's top flight in midweek, meaning there is now just one promotion place to play for with one round of matches to go.
Mainz, in fourth place, are still in the running, along with third-placed 1899 Hoffenheim and Freiburg in fifth.