The German midfielder, who joined from Borussia Dortmund in the summer, started in central midfield as City brushed Borussia Monchengladbach aside 4-0 in the Champions League.
Gundogan had missed the beginning of the season with a knee injury but slipped seamlessly into proceedings for Pep Guardiola's increasingly dangerous outfit.
"Yes I'm really happy – it was a perfect day for me," said the 25-year-old.
"That was my first game for four months and I just tried to work hard, enjoy it and now we're looking ahead to Bournemouth at the weekend.
"It's been tough not playing and not having any real tests other than training and the odd friendly game so to last 80 minutes is very pleasing.
"I'm starting from zero now and looking forward to the weekend."