New manager Peter Stoger says his sole goal is to cajole the best out of Borussia Dortmund after beginning his tenure with a much-needed 2-0 win at Mainz.
Sokratis Papastathopoulos and Shinji Kagawa scored second-half goals as the Austrian made a fine start after replacing the sacked Peter Bosz.
The visitors survived a couple of early scares, including Suat Serdar's shot against the crossbar, to register their first victory and clean sheet in the Bundesliga since September.
It was an encouraging show of resolve from a side which crumbled with alarming regularity in recent months and Stoger, himself dismissed by Cologne this month, hopes to provide the platform for improvement.