Union Berlin went top of the German Bundesliga for the first in their history by edging past Cologne.
An early own goal by Timo Hubers separated the sides, before Union’s Jordan Siebatcheu had a 10th-minute penalty saved by Marvin Schwabe.
The home side were reduced to 10 men nine minutes from time when Luca Kilian was shown a second yellow card.
Unbeaten Union secured top spot after Freiberg were held to a goalless draw by Borussia Monchengladbach.
But it is Urs Fischer’s side who lead the table after six games, ahead of teams such as champions Bayern Munich, who are third and Borussia Dortmund in fifth place.
Union Berlin are also competing in the Europa League after missing out on Champions League qualification by a single point last season.