Dortmund started the game in attacking mode and got their reward after just 12 minutes when Mario Gotze found the bottom corner from an angle after cutting in from the left.
It was 2-0 just three minutes later when Jakub Blaszczykowski found Gundogan in the box for a simple tap-in from close range.
Just before the half-hour mark Dortmund made it 3-0. This time Blaszczykowski was the scorer as he headed in from close range after Gotze found him with a header of his own.
The first-half scoring was far from over, though, and in the 33rd minute Gundogan had his second as he fired low from outside the box.
There was to be one more goal before the break for Dortmund and this time Gotze notched his brace with a good strike from the edge of the box.
After the restart Sercan Sararer came close with a powerful effort from range but just could not find the target.
However, 10 minutes later the five-goal gap was restored when Robert Lewandowski scored after also being set up by Blaszczykowski.