Sterling and City's hierarchy spent much of last season in contract negotiations before the player, whose current deal expires in 2020, put them on hold, preferring to concentrate on England's World Cup campaign.
De Bruyne suffered lateral collateral ligament injury while training with City teammates in August and was ruled out of action for about three months.
"It's a challenge for him - not just for him, for everybody". He was so professional last season and he had competition as well - because Sterling could play in that position on the left.
"If given the opportunity, I want to coach a national team", he said.
Delph, 28, has won seven global caps since he last kicked a ball in anger for City, in the final game of last season. I was delighted to have two weeks watching them.
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The recent worldwide break has again seen City winger Leroy Sane in the headlines over his slow start to the new season.
"It's not about "I don't like you anymore" or "I prefer this one or the other one" - it's not".
Speaking generally about global management, Guardiola, who was linked with the Argentina job in the summer, said: 'In our lives we have dreams of what we'd like to do in the future, but it doesn't mean it's going to happen.
"The journalist asked if we'd sell him for 250million (euros) and I said no, but that is my personal opinion". I do my best and I think Phil is ready.
'After, it is the club and the agent. "Sometimes this kind of thing needs its own time".
"He's very good and is a very dynamic player", Guardiola said.
"Here [City] I feel very good, very protected from football", he said.