Defender CJ Egan-Riley played the full 90 minutes at the Etihad Stadium, as City advanced through to the quarter-finals with a 5-0 aggregate victory.
And Gundogan attributed our of our youngsters' successful progression to the efforts he has witnessed first hand on the training pitch.
He said: "We were able to put out a few young lads today, (it was) great to see them do the work and get rewarded for the work.
"Macca (James McAtee) has already been training for a long time with us, he got a couple of games so you could see already in training all these abilities and potentials.
"CJ, it was his (Champions League) debut tonight and what a debut.
"I’m really happy for the boy, I think he played in a really mature way, avoided simple mistakes and even though he was maybe a little bit nervous and excited, I think he was able to control his emotions very well.
"It shows that hard work always pays off and they deserved it today."
Watch Ilkay's post-match interview in full via the video at the top of this page.