United States global DeAndre Yedlin pulled one back in the 30th minute with his first Premier League goal, becoming the 21st American player to score in the competition.
Newcastle undermined their bid to stifle City during the opening stages by carelessly coughing up possession in risky areas.
The German winger, who was last season's Young Player of the Season, has not started any of City's four matches this campaign, coming on as a second-half substitute in each of their three Premier League games. Can we finish it with six out of six wins?More news: Apple Watch Series 4 Leaks Ahead of Launch
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"Another day it will maybe by Rash [Sterling] out or Riyad [Mahrez] or Bernardo [Silva] or Sergio [Aguero] or Gabriel [Jesus]", Guardiola said.
However, the Newcastle defender is now fit again and will return to the squad in what is arguably the Magpies' most hard game of the season. That is the reason why.
"Last game Phil Foden was not in the squad", Guardiola told his post-match press conference.
"Leroy was so important for us last season and hopefully this season he will be important".
The Magpies totalled just 19% possession during the game and have been heavily criticised by pundits for the negative football played. "But any time it takes them to get back up, we need to take advantage of it". "For me, as a manager, I am really proud of my players".