John Stones will be out of action until after the international break due to an injury, Manchester City manager Pep Guardiola said, casting doubt on the defender's availability for England's Euro qualifier against Ukraine and friendly with Scotland next month.

Stones, 29, suffered a muscle injury during pre-season training and did not feature in wins over Burnley, Sevilla and Newcastle United.

The next international break is from September 4-12, and Stones is set to miss the games against Sheffield United and Fulham scheduled on Sunday and September 2, respectively.

Guardiola is facing additional injury concerns, with Belgian midfielder Kevin De Bruyne sidelined for at least four months after suffering a hamstring injury during City's 3-0 win over Burnley in the opening game of the Premier League season.

Guardiola said he needs the remaining squad to step-up in the absence of key players.

"We will need everyone for this schedule and calendar. We have to come back how the people (City fans) come back. Stones will not be ready until after the international break," the Spaniard told reporters.

The treble winners have lost influential players such as Algerian winger Riyad Mahrez, who left after a trophy-laden spell to join Saudi Pro League club Al-Ahli.

Former City captain Ilkay Gundogan also joined LaLiga giants Barcelona, and Guardiola said "the club will have to take some important decisions about the squad" due to the unexpected exits and injuries.

City beat Sevilla on penalties to secure their first Uefa Super Cup title last week, and Guardiola said he is impressed by his players after a perfect start to the new campaign despite a hectic schedule.

"We already won one title, we are six points from six, score goals and didn't concede many chances against Burnley or against Newcastle...," Guardiola added.

"Rest and go for another one, for another game. When you have that, it's because the team is so special. Otherwise, we cannot do what we have done for many years. It's impossible.

"(The Newcastle game) amazed me and made me so happy because it's still okay - we have to do our best every day (and) they have done it. It was really, really good."