The defending champions kicked off their 2019-20 campaign in emphatic fashion at the London Stadium in a match influenced by the video assistant referee:
Gabriel Jesus opened the scoring in the first half before a second-half treble from Raheem Sterling and a Sergio Aguero penalty.
"In terms of the result, yes. I cannot deny I am delighted for the first game. After winning the last 14 games of last season, that's 15 now. It is good. [But the performance], no. In the first half we were sloppy with our passes, we were not precise. But that's normal. The first game, away, 12:30 kick-off, hot. It's normal. In the second half, from the beginning we were better, more calm, more passes. After 3-0, the game was over."
Sterling, 24, picked up where he left off last season and was the star of the show in east London.
The 2018-19 Football Writers' Association Footballer of the Year produced three fine finishes after the break to finish the hosts off after they had competed well in the opening 45 minutes.
He looked to have registered his first assist of the season as well when he set up Gabriel Jesus at 2-0 ahead, but a historic VAR intervention ruled out the goal for offside:
VAR was influential again when Aguero was allowed to retake his 86th-minute penalty—Lukasz Fabianski had saved his first effort—after Declan Rice was adjudged to have encroached.
While it was not a perfect performance from City, at least by Guardiola's exacting standards, it was a brilliant response to Liverpool's 4-1 win over Norwich City on Friday.
City and Liverpool are widely expected to be the main title contenders again this season.
The Sky Blues are aiming to become the first side since Manchester United between 2007 and 2009 to win three titles in a row, and if they can win 5-0 when not at their best, few would bet against them matching their local rivals' achievement.