Raheem Sterling scored a hat-trick to help City see off West Ham in comfortable fashion, with a goal apiece from Gabriel Jesus and Sergio Aguero too.
City began their quest for a third successive Premier League title with a 5-0 thumping of West Ham at the London Stadium.
Gabriel Jesus got the champions off the mark with a 25th minute strike in a pretty much one-sided affair.
Raheem Sterling doubled their lead six minutes into the second half, before running on to a ball over the defence and finishing coolly past Fabianski for his second.
Sergio Aguero was forced to retake a penalty for City’s fourth and Sterling scored deep in injury time to complete the 5-0 rout.
Riyad Mahrez started on the left flank after being cleared by anti-doping officials to play, and went close with two attempts in the first half before instigating the first goal.
Fresh from winning the AFCON championship, the Alegria international released Kyle Walker whose deflected cut-back was superbly tapped in by Jesus.
City improved into the second period and were rewarded when Kevin De Bryune teed up Sterling to slide an effort under Lukasz Fabianski.
VAR took centre stage for the first time in the Premier League, ruling out Jesus second after Sterling was deemed just offside in the buildup.
The England international made amends for his error later as he timed his run to perfection to cushion Mahrez’s pass before lobbing Fabianski.
And when Issa Diop fouled Riyad Mahrez in the box, City were awarded a penalty that Aguero converted. However, VAR came into action again, requiring the spot-kick to be retaken as Declan Rice appeared to have encroached the area before clearing the ball after Fabianski’s initial save.
City’s no. 10 made no mistake on his second attempt and Sterling had the last say in injury time, converting home a Mahrez’s throughball.
The result means City continued from where they left last season, issuing the perfect response to Liverpool’s 4-1 victory over Norwich on Friday.
West Ham boss Manuel Pellegrini:
“As a manager it is difficult to say you are not happy in the way we worked, especially with how we played in the first 45 minutes. There was not a lot of difference between the two teams.
“Every time that we tried to arrive to their box, they committed 13 fouls. We had just five. We were a little bit innocent.
City boss Pep Guardiola:
“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.”
City entertain Tottenham at the Etihad Stadium on Saturday, while West Ham travel to Brighton the same day.