City's Belgian midfield maestro provided the crucial finish that broke through a stubborn Atletico Madrid defence at the Etihad Stadium.
And the City midfielder acknowledged the challenge posed by the Spanish side was a 'tough' one.
"They play so defensively tight and they are solid, it is their way of playing and I think we played pretty good under the circumstances," he admitted afterwards.
"The first half was tight, and in the second half we had a couple of chances and it was good that we took one."
City boss Guardiola opted to ring the changes midway through the second half, introducing Gabriel Jesus, Jack Grealish and Phil Foden, with the latter providing the assist that allowed De Bruyne to break the deadlock.
"I needed to stay composed and luckily I did, it's very hard.
"They played with almost five at the back and with five in midfield. I recommend anyone that says anything [about us], that they try playing against that on the training ground."
The strike afforded City a crucial one goal advantage to take into the second leg at the Wanda Metropolitano in Madrid, but before that, we will play host to Liverpool in a huge game in terms of the Premier League title race on Sunday, a contest that De Bruyne is relishing.
He added: "It is five days until Sunday. Both teams have played tonight. It is a big game and everybody is looking forward to it including the players."