But the second half was an entirely different story as City played more on the front foot, with De Bruyne and a Riyad Mahrez free-kick completing the turnaround.
This was the first time Kylian Mbappe completed 90 minutes in a Champions League match and failed to attempt a single shot, highlighting PSG's issues.
While City's improvement was most notable in the second period, De Bruyne felt a key alteration was made just before the half-hour mark – it may partly explain why PSG did not have a single shot on target after the 28th minute.
Speaking to BT Sport, De Bruyne said: "It was a game of two halves. We started well in the first 10 minutes but PSG are an unbelievable team and have great quality up front.
"It was a shame the way we conceded. After that they had a couple of small chances. After 25 minutes we changed the way we pressed them and it became better.
"The second half was much, much better. We put them under pressure. The first goal was a little bit lucky with the way it went in, but we played great football and we did well."
Asked to elaborate on Guardiola's instructions at the break, De Bruyne added: "[We were told to] just play a little bit more with the ball.
"The first half, we were a bit too rushed, trying to go forward too quickly and that's not the way we are set up as a team.
"In the second half we tried to find space more patiently. They're a tough team to play against. The progression we made as a team was good."
The victory puts City in charge of the tie as they look to reach their first-ever Champions League final.
The omens are good for them as well: in the history of the European Cup and Champions League, there have been 47 previous instances of an English side winning the first leg of a two-legged knockout tie away from home, and on each occasion that team has progressed.