The only word to describe it is bedlam. Manchester City are the champions of England but where do you start? How, seriously, can it be possible to sum up the raw, shredded emotion of those final, exhilarating moments, the scale of what it means and the sheer drama that unravelled before the party could begin and the Premier League trophy was in Roberto Mancini's hands?

There can be only one other moment to compete with this and it was Michael Thomas's title-winning goal for Arsenal at Anfield in 1989. Mancini's team played with their supporters' nerves to the point of brutality. They were 2-1 down going into stoppage time, on the verge of a defeat so harrowing they would never have been allowed to forget it. There were supporters leaving the ground in tears, scarcely believing the team could have been so reckless.

What happened next was so extraordinary it is difficult to know if there are enough superlatives in existence to do it justice. Edin Dzeko's header to make it 2-2 came in the 92nd minute, at a point when the crowd were watching in almost numb disbelief. On the sidelines, Mancini and his coaching staff could be seen imploring everyone to go forward, desperately relaying the news that Manchester United were winning at Sunderland. Except City had played dismally all afternoon, consumed by nerves against the team with the worst away record in the league. Queens Park Rangers had fought back from a goal down, despite the latest red card for the Joey Barton portfolio of shame.

The London club have avoided relegation courtesy of Stoke City's draw with Bolton Wanderers but their manager, Mark Hughes, described himself as "flat" later on, still trying to work out how his team had been beaten. City, he said, had "lost all direction". He, like everyone else, was bamboozled by what had happened.

It goes like this: four of the five minutes of extra time had elapsed when Sergio Agüero found himself with the ball. He was inside the penalty area, on his right foot, and it was then that everything suddenly seemed to go into slow motion. This was the moment football blurred with pandemonium.

His shirt was off, the victory run had started and the stadium was a mosh pit of flailing bodies. City had wrenched the title out of Manchester United's grasp, with 60 seconds to spare and the Etihad Stadium crowd roared and sobbed and bounced and screamed. Mancini talked later on of worrying about his father Aldo, remembering he had suffered a heart attack two summers ago.

When they have time to take a deep breath City will reflect that they really ought to have made this a far easier assignment once Pablo Zabaleta had moved forward from right-back, six minutes before half-time, and fired in a shot that looped off Paddy Kenny's glove and dropped in off the far post.

At that stage QPR had played as though in a straitjacket, barely venturing out of their own half. Kenny should have kept out Zabaleta's shot and it was reasonable at that point to believe a team that has dropped only two points at home all season would go on to emphasise their superiority with more goals. Except this was a day when the most financially powerful club on the planet threatened to revert to those years when they somehow always contrived to mess it up and leave the joke on themselves.

The entire complexion of the game changed three minutes into the second half when Shaun Wright-Phillips flicked a hopeful pass forward and Joleon Lescott's mistimed header allowed Djibril Cissé to run clear. The striker advanced towards Joe Hart and thumped his drive beyond the goalkeeper.

What followed was extraordinary even before we reached those final, stupefying moments. After 55 minutes Barton tangled with Carlos Tevez on the edge of the penalty area and the Argentinian went down, clutching his face. The referee, Mike Dean, brought out a red card and it was then it became apparent Barton was not going to go quietly. This was a street-fighter masquerading as a footballer, exposing the myth of being a changed man.

Agüero was then felled from behind, with a snide kick to the back of his legs. Suddenly Barton seemed intent on trying to prolong the argument with anyone in his proximity, shoving his head towards Vincent Kompany's face and moving aggressively in the direction of anyone in blue. Even as he was manhandled to the side of the pitch, he was trying to get at the City substitute Mario Balotelli. Mancini was on the pitch, ordering Kompany away from the flashpoint as City's players sought retribution.

Barton has no mitigating circumstances and his recklessness could have had ghastly consequences for his team. He deserves the club fine that will come his way and the FA will almost certainly have to act. If Hughes has any sense, he will also remove the captaincy because if ever there was an example of a player not understanding the true qualities of leadership, this was it. Hypothetical or not, it is no exaggeration to say QPR could have been relegated because of his stupidity. The strange thing was that QPR actually improved when they were down a man.

City were tense, nervous, rushing passes, unable to find their usual rhythm despite having a huge amount of possession. Then, on 66 minutes, a sudden, damp silence fell over the stadium as QPR broke, the substitute Armand Traoré crossed from the left and Jamie Mackie's header gave the away side the lead.

After that, there were periods when City seemed totally devoid of ideas but, to their credit, they always kept going. Everyone in the stadium knew United were winning and that, if this was the return of "Cityitis", it was going straight in at No1 in the list of games that would always haunt them. But then the board went up for extra time and football, bloody hell.