Goals from Riyad Mahrez, Gabriel Jesus, Phil Foden, and Aymeric Laporte were more than enough to beat the struggling Arsenal side with Mikel Arteta losing his third game against his former boss Pep Guardiola.
Some questionable decisions in the starting eleven, as most people hoped William Saliba could make his senior debut, and no one knew what to expect of Alex Rúnarsson in the goal.
The game started on the wrong foot as Gabriel Jesus put the visitors ahead with barely two minutes on the clock.
Arsenal's defensive performance could be questioned during the first goal as Jesus could score among three defenders.
The Gunners' first dangerous attack led to an equalizer by Alexandre Lacazette after a superb effort from youngster Gabriel Martinelli who was the best Arsenal player on the pitch but the one-man army could not do enough.
The second goal came from Riyad Mahrez's free-kick but the Icelandic keeper seemed to be able to cover it easily but somehow the ball slipped through his gloves. A costly mistake but the young keeper seemed shaky all night long when he was tested.
An interesting question to be asked what can he provide for Arsenal that an academy player could not?
While he seems to be good with the ball at his foot, his goalkeeping abilities need polishing, to say the least. Let's not forget he occupies one of the non-English spots in the team as well.
Why not Saliba?
Mikel Arteta said numerous times that William Saliba is not ready to be included in the senior team, and he will get his chance when the time is right.
Many hoped that this is could be the perfect opportunity for the talented central back to earn his first start, but he was not included in the squad at all.
Arteta went with Shkodran Mustafi to pair with Gabriel Magalhaes instead which, in retrospect, was not ideal against Manchester City, and the whole defense looked shaky.
The other problem with this is that Mustafi has already indicated that he wants to leave this summer and won't sign any contract with Arsenal. So why play him, and not give a chance for a youngster to prove himself?
Martinelli is great
The Brazilian youngster made his long-awaited return after a horrific injury last season. There were worries about whether this injury will affect his pace or explosiveness but he was everything the fans hoped for.
Martinelli played with hunger, and every time he got the ball he was looking to attack, beat his defender one on one, or find his teammates with a cross.
Arsenal's only goal came from his efforts as his first cross was cleared but after regaining the ball, his second attempt found Lacazette perfectly.
Just before the break, he gave Arsenal fans a heart attack after a clash with Manchester City keeper Zack Steffen. Martinelli went down and it seemed serious but fortunately, he was able to continue. To avoid any risks Mikel Arteta took him off in the 49th minute, but the youngster showed why many fans waited for his return.