Schalke's good start to the season came to a halt at the PreZero Arena. The team from Gelsenkirchen, who could have been top of the table after eight matchdays, succumbed in the closing stages. The opportunity arose because Wolfsburg, Bayern and Leipzig all failed to win.
The away side failed to take their chances and the home team punished them. Andrej Kramaric made it 1-0 in the 71st minute before Ihlas Bebou of Togo sealed the deal five minutes from time.
Schalke were defeated for the second time this season and they are in seventh just one point off Leipzig, Bayern and Dortmund. Schalke are just two behind leaders Gladbach and second placed Wolfsburg.
Earlier in the day, Cologne moved out of the relegation zone after defeating basement boys Paderborn 3-0.