At his pre-game press conference, the City boss was first asked whether he was concerned that De Bruyne wasn’t quite at the incredibly high standards he sets himself so far this campaign.
Guardiola says the Belgian playmaker, still working his way back to full fitness after being injured at the European Championships, cannot always be at optimum levels.
“You cannot imagine how good he is,” said Pep.
“When you are playing millions of games, you have highs and lows. I know what he is doing.
“The way he trains. He knows he has our support always. I was a player and you cannot perform incredibly well all the time. He has highs and lows. He knows better than anyone where he can be better.
“We forget they are human beings. In the last eight or nine years, they have had a three-week holiday every year.
“Fatigue can take influence. For the players, they have the physical strength it is easier.
“There is no human being who can play in a creative way every three days. They cannot do it.”
The boss was also asked if he believed Gundogan could play a similarly crucial role this campaign to last season’s.
He replied: “Every player is so important. You have to understand there are injuries and highs and lows in careers.
“What a player did lasts season doesn't mean he will do it again.
“Ilkay is so important, you know, he is intelligent, always thinking what is best for the team, but he was injured and needs time.
“He is getting better and we need him like we need all the players. He will; be much better in a few months and there are others who need to play now because they are in top form and may drop later.
“You have ,maintain it every day. That's why these players get credit for the last 6 years because it’s every day. Tomorrow we have a chance.
“The group stage every year is more tricky. We already lost and now the games at home we have to take it.
“Tomorrow we have an incredible opportunity to step forward.”
City host Club Brugge on Wednesday 3 November and we’ll have full coverage here on mancity.com and the official App.
Kick-off is at 20:00 (UK) and our Matchday Centre will begin two hours before, bringing you live updates throughout the evening, whilst our Matchday Live show gets under way at 18:45.
A match report and all the post-match reaction will be available shortly after the final whistle and you can watch highlights from midnight after the game.
CITY+ subscribers can also enjoy a full-match replay from midnight.