Darron Gibson provided former club Manchester United with a vital boost in the title race to extend Everton's remarkable hoodoo over Roberto Mancini.
Gibson's first goal since his £500,000 move enabled United to go level on points with Mancini's league leaders and ensure City have now only one victory from their last 21 visits to Goodison Park.
The Republic of Ireland international's arrival earlier last month was not warmly welcomed by Everton supporters but this telling contribution could hand the initiative back to his old employers.
Goodison Park may have proven a pain for Mancini but Manchester City's struggles there have been even more frustrating over the years.
City always seem to come unstuck against the Toffees and went into this clash desperate for a fourth successive league win.
Mancini's title chasers could have been behind after just six minutes but for the presence of a former Everton favourite.
Denis Stracqualarsi's header from Leighton Baines' corner beat Joe Hart but Joleon Lescott hacked the ball off the line before City's defence cleared.
City have stumbled in recent weeks, losing their first two league games of 2012 and exiting both Cups in the space of 17 days.
But they were clearly on a mission to end their Everton hoodoo and Gael Clichy, Edin Dzeko and Sergio Aguero all slashed shots wide from decent positions.
At least Moyes can power up his own bid for a top ten finish after the £5.5m signing of Nikica Jelavic from Rangers.
Jelavic was sat in the stands and is set to be a direct replacement for Louis Saha, who was not even named in the Everton squad.
And the Croatia international saw Everton nearly sneak ahead ten minutes before half-time but Marouane Fellaini bundled Stracqualarsi's cross past the near post.
But Samir Nasri came closest to breaking the deadlock a minute later with a devastating drive from 35 yards that came crashing back off the crossbar.
Play was temporarily suspended shortly before the break when an Everton supporter handcuffed himself to Hart's post.
It was a bizarre incident, and Hart watched on bemused as police took five minutes to untie the pitch invader with bolt cutters before leading him off.
City dominated the early stages of the second half but failed to make the most of their openings.
And Gibson punished their profligacy on the hour to earn instant cult hero status with a drive that deflected off Gareth Barry.
It was Gibson's first Premier League goal since March 2010 and time will tell how influential it proves for his old club in the race for the title.
Gibson almost powered in another as City wilted and Mancini's misery was complete when Phil Neville escaped punishment for a clear handball in the penalty area from David Silva's cross.