England international Sterling has started just two of Manchester City's last eight games in all competitions.
The 26-year-old sat out all but the last two minutes of Wednesday's memorable Champions League victory over Borussia Dortmund having remained on the bench throughout the first leg of that quarter-final tie last week.
Others, notably Phil Foden, have shone in his place but Guardiola claims that does not indicate Sterling has fallen down the pecking order.
The City manager said: "The trust with Raheem is intact. It is the same as when we arrived here.
"He has our confidence and the quality is there. I cannot give the players confidence, they have to have it for themselves, but 'Rash' has a lot of experience.
"What we've done these incredible years, with the amount of titles won and how many records we have broken in the process, Raheem was key and is a key player.
"Everyone says it is impossible but in football anything can happen. We could lose four or five games in a row. In football it can happen.
"It has happened before, which is why you have to stay in the present."
Guardiola has confirmed number two goalkeeper Zack Steffen will play against Chelsea in place of Ederson, as he has done in previous domestic cup ties this season.
He said: "Yes, he'll start. Always I've done it like this. If he doesn't play I'd lose the team and better to lose games than the team."