The Bundesliga champions were very much second best in the first quarter of the match, despite enjoying much of the possession at the Allianz Arena.
"We played really well but in the first 20 minutes, Manchester City were the better team," FourFourTwo quotes Guardiola as saying. "We started with four players in our defence because I knew that City planned to stay really close on the byline with [Samir] Nasri and [Jesus] Navas.
"Nevertheless we couldn't dominate the game. We had a lot of problems with Nasri and Navas. After 20 minutes we changed the system, with two players in the middle and after that we played much better.
"In the last 15 minutes of the second half we dominated the game - we created a lot of chances, but it's not easy against Manchester City. We played with passion and that's why we earned this win today."
Next up for City in Group E is a home match against Roma.