Ake rose highest to powerfully head in City's first of six goals against the Bundesliga side.
Riyad Mahrez, Jack Grealish, Joao Cancelo, Gabriel Jesus and a Nordi Mukiele own goal propelled City to three points in Pep Guardiola's 300th game as City manager.
DOWNLOAD THE MAN CITY APP
The Dutchman revealed that his boyhood dream of scoring in the competition was fulfilled under the lights at the Etihad.
"The balls in were perfect, I'm so happy to score my first one, hopefully many more to come," he said.
"Last year I was close [to scoring], this year to get it in the first game is what you want as a little boy. To play this kind of stage and to score is amazing.
"Every time they got back in the game, we scored quite quick again so you make their hopes less. I'm happy with that."
The centre-back also spoke about City's attacking prowess, what the squad will do to improve defensively and whether he'll be making a happy call to his family tonight!
Watch the entire interview via the video at the top of the page.