"It's not easy to win 5-0 at home against another Premier League team," Edin Dzeko said afterwards.
That may well be the case, but winning 6-0 certainly seemed easy enough, and City - helped by a hat trick by Alvaro Negredo - will surely be lining up at Wembley for the Capital One Cup final in March.
"We still have to play away," cautioned Dzeko. "But this will give us the confidence for the second leg. The first goal is always important, then maybe we can open them up because they were defending with eight, nine players always."
Yaya Toure was also on the scoresheet as City piled on the misery for Sam Allardyce, the under-fire West Ham United manager.
The hosts needed just 12 minutes to take the lead at the Etihad Stadium as the Londoners were swept aside in an embarrassingly one-sided match.
Allardyce, who was taunted by visiting fans late in the game, had prioritised the match by fielding a weakened side against Nottingham Forest in the FA Cup last weekend.
But it was quickly evident that the strategy had backfired as they were thrashed by six goals, and despite eight changes - including the return of senior players such as Mark Noble, Joe Cole, Guy Demel and Mohamed Diame - they slumped to a similar defeat in the Manchester rain.
It was also a particularly chastening debut for Roger Johnson, who looked well off the pace after arriving on loan from Wolves this week to apparently bolster the defence.
For the hosts, it was another irresistible display to add to a growing catalogue that has already seen them put six past Arsenal and Tottenham and score seven against Norwich at home this season.
In truth, they might even have had more but for a number of good saves from West Ham goalkeeper Adrian.