Manchester City's 6-1 thumping of Alex Ferguson's Manchester United in October 2011 sent shockwaves throughout the football world.

Roberto Mancini's team's evisceration of their illustrious rivals at Old Trafford served booming notice of Premier League title ambitions that would be dramatically realised the following May.

Since that day, City have claimed four top-flight crowns to the one that marked Ferguson's 2012-13 United swansong.

As such, talk of a powershift in Manchester is often pinned on a game simple known as "the 6-1" in City circles.

However, there is an argument that a derby win 200 miles south of Manchester at Wembley Stadium six months earlier was more significant in terms of laying the foundations of what was to come.

Yaya Toure scored the only goal in that FA Cup semi-final on April 16, 2011, a day when Mancini's hastily yet carefully assembled City began to scent everything was possible.

FORZA MANCINI

Unlike the current incumbent of the Etihad Stadium hotseat, current Italy boss Mancini will not feature in many conversations debating the finest coaches of this generation.

An impressive CV, featuring Serie A and Premier League success, is checked in the eyes of some observers due to the respective factors of his Inter benefiting from Juventus' punishment in the Calciopoli scandal and a bulging Abu Dhabi war chest at City.

Then there are the frequent short-tempered altercations with players that result in few former charges burnishing the Mancini legend.

However, there can be little doubt that the hard-headed and tactically sharp Sampdoria great was exactly the right man at the right time for Manchester City.

As evidenced by a touchline spat the following season, Mancini relished the challenge of head-to-head combat with Ferguson – an attitude that quickly seeped through a club that had generally dreaded derby day for two decades.

A profile by The Athletic recently detailed how City's team bus went the wrong way to Wembley en route to the United match and Mancini, very much the superstitious type, made the driver repeat the convoluted route ahead of the final against Stoke City.

They were the only wrong turns he took when navigating the pursuit of his club's first silverware for 35 years, with two of his major signings coming to the party on cue.

TOURE THE MATCH-WINNER

Despite some scattergun buys, particularly after Sheikh Mansour's takeover went through in September 2008, Mark Hughes left Mancini a useful inheritance. Joe Hart, Joleon Lescott, Gareth Barry, Pablo Zabaleta and captain Vincent Kompany would all go on to be pivotal figures in the 2011-12 title win.

City's 2010 close-season haul of recruits was expensive but astutely put together, as David Silva, James Milner, Aleksandar Kolarov, Jerome Boateng and Mario Balotelli all arrived alongside Toure.

That £24million signing from Barcelona was derided in some quarters – Toure was an average player who neither created nor scored goals, in Paul Merson's judgement.

As hilariously as those words read now when considering one of the Premier League's great midfield players, it was easy to view the big Ivorian as possibly surplus to requirements. A holding player at Barcelona, Mancini already had Barry, Nigel de Jong and an ageing Patrick Vieira for such duties.

Of course, Toure would prove to be so much more than that, unleashed ahead of the De Jong-Barry midfield base to wreak havoc. He seized upon Michael Carrick's early second-half mistake at Wembley, smoothly accelerated beyond Nemanja Vidic and slotted past Edwin van der Sar to spark bedlam in the City end behind the goal.

Toure also scored to sink Stoke in the final and he frequently proved himself as the man for the big moments thereafter. He hit a brace at Newcastle United to bring the title within touching distance in 2012 and scored remarkable solo goals against Crystal Palace and Aston Villa to do likewise two years later.

The 2013-14 season also saw Toure spark a 3-1 comeback win over Sunderland in the EFL Cup final with an outrageous long-range finish. In 2016, he netted the decisive penalty to see off Liverpool in the same showpiece.

There were three more Manchester derby goals on the back of his Wembley heroics – two of those in resounding victories. City had found their ultimate clutch player.

THROW BALOTELLI IN JAIL

Toure's winner almost instantly injected a swagger into Manchester City that was impossible to equate with the squad that seemed to stagger apologetically into the national stadium.

A 3-0 thrashing at Liverpool on the preceding Monday and a hamstring injury to attacking talisman Carlos Tevez meant furrowed brows long before the satnav went rogue en route to Wembley.

United remarkably scored three injury-time winners in four derbies the previous season – including one in the EFL Cup semi-final – and Wayne Rooney's overhead kick to settle the February encounter at Old Trafford lay fresh in the memory.

Dimitar Berbatov passed up two glorious chances in quick succession, sliding the ball over from three yards after Joe Hart saved superbly. It felt like a matter of time until a United side still chasing a treble at that stage would make their superiority count.

But then two of Mancini's headline acquisitions set about shifting the contest in City's favour. David Silva shuffled and cajoled his attack up the pitch, deftly tying United up, silken thread by silken thread.

Already a European champion and World Cup winner with Spain at this stage of his career, Silva gracing the big occasion with aplomb was no more surprising than at any other point over the past decade. The same could not be said for the inimitable Balotelli.

The madcap charm of the Italian's early days in Manchester had lost much of its shine over the previous month. In a 2-0 Europa League defeat at Dynamo Kiev, Balotelli was substituted after suffering an allergic reaction to the grass.

In the return leg, City claimed a 1-0 win – their exit relatively valiant as it came with 10 men after Balotelli plunged his studs into Goran Popov's chest in the 35th minute. He was also said to have thrown darts at youth-team players to cap his own personal take on March madness.

A stricken Tevez clearing the way for Balotelli to start against United looked a recipe for further nonsense, but the enigmatic forward harnessed and channelled his lavish gifts.

Only Silva (four) created more than the two chances the ex-Inter youngster crafted for City, and Balotelli's four shots saw him threaten the United goal more frequently than any of his team-mates, all the while intelligently occupying the formidable centre-back pairing of Rio Ferdinand and Vidic.

Balotelli dropping deep and fashioning space for a rasping 35-yard strike that Van der Sar had to turn over was the moment in the game City came up for air and belief seemed to flow thereafter.

Their centre-forward played like a grown-up right up until the final whistle, when he made a beeline for Ferdinand and sparked a brawl that Mancini pulled his perplexing protege away from.

"Every time something happens it seems to be Mario's fault," the City boss remarked. "If he did celebrate in front of the Manchester United supporters, I don't know, we can put him in jail if you like."

TEARING DOWN THE BANNER

Even if a permanent change in Balotelli's output would prove beyond Mancini, he arguably propelled a shift in his club's collective mindset in that FA Cup semi-final.

"If we win the FA Cup, then next season I think we can play for the title because we improve our mentality and we can improve our team," Mancini said afterwards. City did both those things.

United's frustrations as the afternoon progressed, demonstrated by Paul Scholes' red-card lunge on Zabaleta, suggested an awareness of what their lax showing was about to unleash.

City have not entered a derby as clear underdogs since. Once a club embarrassed by a trophy drought and Old Trafford's mocking ticker banner, six of the past seven major trophies contested in English football have ended up at the Etihad Stadium.

The vast sums spent on Sheikh Mansour's Eastlands project can make that return feel inevitable, but that was not the sense at Wembley in April 2011 as Mancini's players giddily joined their supporters in the backs-turned Poznan celebration at full-time, lapping up that first dizzying encounter with possibilities.

The 6-1 might be the result City fans still crow about at every derby, while Sergio Aguero's last-ditch escapology against Queens Park Rangers claimed a slice of football history never to be forgotten.

But without Toure's Wembley winner on a day neither as bombastic or cinematic as those high-water marks, the path to glory would have at best been delayed and very different indeed.