It is the moment that defines the Premier League era. A flash of brilliance by Sergio Aguero, three minutes and 20 seconds into stoppage time, on the final day of the 2011-12 season, which delivered Manchester City their first title in 44 years.

Roberto Mancini's City had left it so late against Queens Park Rangers that, 140 miles away at Sunderland, Manchester United's players were still on the pitch at the end of the game at the Stadium of Light believing that they were champions.

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But while Premier League officials began to unpack the boxes of winners' medals in the tunnel at Sunderland following United's 1-0 victory -- with the clubs level on points at the start of the day, the league had a trophy and medals at both games -- City scored twice in the space of two minutes of stoppage time to turn the season on its head and spark scenes of bedlam inside the Etihad.

And as for the scenes at Sunderland when Aguero scored City's winner, you will probably have seen the picture of United's Phil Jones with his head in his hands by now ...

It is remarkable to think that it is eight years since Aguero's goal sealed City's title. Edin Dzeko, who made it 2-2 and gave City hope with a 92nd-minute header, tends to be overlooked in the story of an incredible day, but without the Bosnian's goal, there would be no Aguero moment or City title.

I was at the Etihad that day, reporting on the final day of an unforgettable title race that had swung between United red and City blue from the opening day of the season. With six games to go, United held an eight-point lead, but a 4-4 draw at home to Everton and defeats against Wigan and City had enabled their neighbours to climb to the top by virtue of goal difference going into the final day.

City simply had to win at home against Queens Park Rangers, who were still fighting against relegation in 17th position. Meanwhile, United travelled to Sunderland needing to win their own game and hope for City to drop points at the Etihad to win the title on the final day of the season.

Yet it was anything but simple for City. The afternoon of May 13, 2012, would prove to be a wild roller coaster of emotions that takes City from the depths of despair to the peak of ecstasy. The opening 45 minutes are bumpy enough. When news filters through of Wayne Rooney's 20th-minute goal for United at Sunderland, the Etihad falls silent. It becomes edgy, with fans venting their frustrations at the players or simply leaving their seats due to the unbearable tension.

During his reign as City manager in the late 1990s, when the club spent a season in the third tier of English football, Joe Royle coined the phrase "Cityitis" to describe the team's unerring ability to mess things up. With City struggling to make headway against a team of strugglers, the mood within the stadium suggests that Cityitis is rearing its ugly head again, but five minutes before half-time, Pablo Zabaleta scores to make it 1-0 and the formality of victory seems assured.

But the noise is reduced to mute again at the Etihad when Djibril Cisse equalises for QPR three minutes into the second half after a defensive mix-up between City defender Joleon Lescott and goalkeeper Joe Hart. Cityitis again?

City are given hope seven minutes later, though, when their former midfielder Joey Barton is sent off for kicking Aguero. Even without Yaya Toure, who limped off with a hamstring injury at half-time, City now surely can't mess it up, could they?

But 11 minutes after QPR are reduced to 10 men, they stun the Etihad again by regaining the lead with a goal by Jamie Mackie. With United still leading at Sunderland, City now need two goals, against 10 men, in the space of 24 minutes to win the league. But it is slipping away. Fans are in tears and the silence has now been replaced by shrieks of anguish. It sounds like a wake.

The clock ticks on. The press box at the Etihad is among the supporters, close to the food and beer stalls in the concourse and, as time drifts by, the supporters begin to abandon hope. They start streaming up the steps, heading for the exit doors. At 80 minutes, it looks like an exodus has started, but those supporters who want to escape the torture chamber discover that the exit doors are locked to stop those fans outside, without tickets, from sneaking in to watch the closing stages.

So those fans who have lost faith in a miracle are wandering around the wide aisles of the concourse, unable to escape, but refusing to watch the calamity unfolding on the pitch.

The clock hits 90 minutes, City are still losing 2-1 and have just four minutes of stoppage time to save their season.

Some fans inside the ground will have been at Wembley 13 years earlier, when Royle's team scored twice in stoppage time to come back from 2-0 down to take their third-tier playoff final against Gillingham into extra time. City would go on to win that game and promotion on penalties.

City fight to the end, they always do, but two goals inside four minutes to win the title? Come on.

The final whistle blows at Sunderland and United have won. They are simply waiting for the game to finish at the Etihad so they can get their hands on the trophy again.

Then Dzeko scores, heading in from six yards, and all those fans who had been walking around like zombies in the concourse begin to stream back in. People are falling over in the rush, stumbling on the steps as they hurry back to celebrate Dzeko's lifesaver.

Fans regain belief, they urge the players on for one last surge. The noise begins to crank up, a mixture of howls and screams, cheers and expletives.

The game restarts, there are still two minutes to play and the QPR bench erupts. Mark Hughes, his staff and the substitutes leap out of their seats and some run onto the pitch, celebrating news that Bolton have lost at Stoke and, as a result, QPR are safe from relegation, even if they lose.

Is it a decisive moment? QPR know they are safe and, as City pour forward, the visiting players switch off to allow Mario Balotelli space on the edge of the area.

The Italian threads the ball through to Aguero inside the penalty area, the City striker takes a touch and then unleashes an unstoppable right-foot shot past goalkeeper Paddy Kenny to score the goal that wins the game and the title and sparks scenes of frenzy inside the Etihad.

Aguero races off, twirling his shirt in the air, Mancini is on the pitch, Hart is racing around with his arms outstretched and Balotelli, who has just produced his one and only assist of the season, catches up with Aguero to celebrate. Those fans who had rushed back in are now a mass of bodies, jumping rows of seats and falling over.

And up at Sunderland, Sir Alex Ferguson has heard the news. The United manager summons his shell-shocked players off the pitch and into the dressing room. Some of them walk past the Premier League officials as they hurriedly pack up the medal boxes and retreat to a side room.

"We deserved it," Mancini said after the game. "I have never seen a finish like it. Crazy, crazy."

One goal changed everything. It came on 93 minutes and 20 seconds and you will never see another ending quite like it.