Arsenal, with the help of a very late strike from Spanish midfielder Mikel Arteta, completely destroyed Manchester City's hopes of winning this year's Premier League title by registering a 1-0 victory against them at the Emirates.
Mancini, who will also probably be kissing his job at City goodbye, must have made one of the worst managerial decisions of his life by dropping many players including Micah Richards, Kolo Toure, Nigel de Jong, Aleksandar Kolarov, Edin Dzeko and David Silva. In addition, the decision to play the controversial Mario Balotelli proved to be a very wrong decision as the 21-year-old striker was sent off after being shown two yellow cards.
Arsenal, who dominated for long periods, made a strong start to the game. They were clearly the better side, creating more chances, working harder and hit the woodwork a number of times.
Also, the hosts sent a number of crosses over City's six-yard box, which kept defenders Vincent Kompany and Joleon Lescott and goalkeeper Joe Hart very busy.
The Gunners nearly took the lead before half-time through Robin van Persie's brilliant header, which unfortunately struck teammate Thomas Vermaelen.
Meanwhile, Balotelli just escaped getting a straight red after he crashed into Alex Song with his studs; the Italian seemed to have neither a chance to win the ball nor indeed any desire to. However, referee Martin Atkinson decided not to punish the controversial star.
Just after this incident, Balotelli nearly put his team in front, when he managed to break off from his marker and connect with a corner. However, his shot was blocked and cleared by Arsenal skipper van Persie.
The Gunners kept piling pressure on City but they could not get through thanks to some resolute defending by Kompany and Lescott.
With the start of the second half neither team seemed to be getting the right attacking momentum as both teams failed to penetrate each other's defence.
City missed a golden opportunity, when Clichy sent out a low and dangerous pass towards Argentinean star Segio Aguero, who looked very determined to score. However, a collision with teammate Pablo Zabaleta took the power off his shot which was finally tipped over the bar by Arsenal goalkeeperSzczesny.
The Gunners finally took the lead in the 87th minute through a brilliant shot by Mikel Arteta, who managed to find the net from 25 yards despite a desperate dive by Joe Hart.
This result, after the Red Devils' win over QPR, means Mancini's men are all but out of the race for securing this season's Premier League title.