Watford were totally destroyed in an incredible opening 18 minutes during which the champions scored five times.
If the champions were still angry at last weekend’s defeat to Norwich, it was Watford who paid a heavy price.
With 18 minutes of this game gone,City had scored five times. Five times.
It was mesmerising football that the short-sleeved capacity crowd lapped up in the early autumn sunshine.
Where to begin?
Silva started the rout as he arrived at the optimal moment to turn in Kevin De Bruyne’s superb low cross with just 52 seconds on the clock.
And the celebrations had barely died down as Watford came within a whisker of equalising through Gerard Deulofeu’s clever run and low shot that was palmed around the post by Emerson.
City soon doubled their lead, though, with De Bruyne racing forward before feeding Mahrez who was brought down by Ben Foster – a clear penalty.
Aguero stepped up to stroke home his eighth of the season and his 100th Etihad goal – a feat only achieved by two other players in the Premier League era.
The third, on 12 minutes, was all about Mahrez who danced past a number of challenges before being felled on the edge of the box – he took the resulting free-kick which deflected in off Tom Cleverley.
And the goals kept coming.
With Watford’s porous defence looking like they might concede with every attack, De Bruyne whipped in a corner that was nodded across goal by Otamendia and headed home by Bernardo on 15 minutes.
Three minutes later, Otamendi slid home Aguero’s low cross to make it five.
It was ruthless attacking football by the rampant Blues, and it was quite a way to mark the Club’s 125th anniversary celebration.
There were further opportunities, but for the final 27 minutes or so, Watford rode their luck and the Blues eased off the gas a little.
But the ceasefire ended just three minutes after the re-start as persistence by David Silva and Bernardo eventually ended with an opportunity for the Portuguese play-maker who neatly gathered the ball before slotting it past Foster for his second of the afternoon.
The popular former Monaco man completed his treble on the hour-mark, after a sublime Mahrez pass found De Bruyne who claimed yet another assist as his low cross was poked home by Bernardo.
Angelino, who replaced Mendy at the break, made some excellent raids down the right and his pinpoint cross almost resulted in No.8 as Mahrez thumped the crossbar with a header.
Eric Garcia and Joao Cancelo also came on for brief cameos before De Bruyne ensured the Blues had their biggest Premier League win with a thunderous drive on 85 minutes.
It was no more than KDB deserved. He was brilliant from start to finish.
Man City reduced the gap on leaders Liverpool to just two point ahead of the Merseysiders’ Sunday afternoon trip to Chelsea which could be difficult against Lampards young on form side.