What drama. What a game. What a second half. The final will struggle to live up to this spell-bounding semi-final. Manchester United set up a Wembley date with Aston Villa when Wayne Rooney struck in injury time.
he roar was ear-splitting, United fans raising the roof. If Rooney will get the headlines, City deserve huge praise for playing a full part in this astonishing occasion.
Roberto Mancini's centre-halves, Vincent Kompany and young Dedryck Boyata, had been outstanding all night, making vital interceptions.
Carlos Tevez -- who else? -- looked to have dragged this extraordinary tie into extra-time but Rooney, United's darling, the embodiment of the champions' attacking principles, had the final word.
When Ryan Giggs, rolling back the years with another exceptional display, bent in a cross from the right there was Rooney meeting the ball with a classic centre-forward's header, adding to earlier goals from Paul Scholes and Michael Carrick on a stunning footballing occasion.
Even before Scholes had struck early in the second period, the temperatures had begun rising.
With tensions running high, the authorities had left nothing to chance, even putting a policeman in the middle. Referee Howard Webb, occasionally of Rotherham constabulary, had a busy first half, always quick to intervene if the neighbours squared up.
It simmered throughout the opening 45 minutes. Nani followed through on Pablo Zabaleta, who was then caught by Rooney.
Scholes went in so hard on Shaun Wright-Phillips that he almost broke the hyphen. If hardly the dirtiest Manchester derby in history, fouls punctuated the game.
Rafael dived in recklessly on Craig Bellamy, who had read the Brazilian's intentions and leapt out of the way.
The fans loved the commitment, the duels. City supporters stoked up the atmosphere with chants of "there's only one Malcolm Glazer'', the B-side of their latest song being the suggestion to United fans, in less than delicate terms, that Manchester, in fact, belonged to those in blue.
Those in the red corners were having none of it. Even the club couldn't resist a dig, pointing out in the programme that City's last trophy had come in 1976, adding "in case you are wondering United have lifted 28 major trophies since then''.
Sadly, Bellamy was hit by a coin in that tumultuous second half. Everyone had known this would be a tense night on and off the field.
Ferguson had paid City the compliment of appealing Ferdinand's English FA charge, allowing the centre-half to face Tevez.
Manchester City manager Roberto Mancini had deployed Bellamy and Wright-Phillips out wide with a remit to support Tevez.
Detecting when the Argentinian was in possession was hardly difficult. The Stretford End dissolved into abuse. Tevez's tussle with Ferdinand was a key duel, the United defender being foolish enough to wave an arm that caught Tevez, sending him crashing to the floor, clutching his face. There was definite contact but Webb deemed it unmalicious.
Tevez then raced down the inside-right channel, arrowing towards United's goal, stopped only by Ferdinand's sliding interception, which seemed to take the player as well as the ball. It looked a penalty but Webb waved play on. City had threatened mainly on the counter in the first half.
Wright-Phillips beat Patrice Evra and whipped in a cross that Bellamy met with a header, forcing Edwin van der Sar into emergency action.
United were grateful to their tall Dutchman for another save, a low stop to keep out Tevez's stooping header. If Tevez was City's focal point, Rooney was inevitably United's.
Using Rooney as the lone front-runner, Ferguson had flooded midfield, deploying Scholes deep, allowing Michael Carrick and Darren Fletcher to push on while Giggs patrolled the left and the right-sided Nani sought to protect Rafael from Bellamy's raids.
Rooney was always a threat, turning Micah Richards and bringing a low save from Shay Given, who then clutched an effort from Giggs.
United, needing to score, increased the tempo after the break.
The half began nervously for the holders, Richards holding off Rooney and unleashing a left-footed strike that Van der Sar brilliantly clawed away.
This was a real scrap, occasionally spilling over. When Tevez slid in legitimately on Rafael to chase a loose ball, Ferdinand and Scholes were quick to remonstrate, ensuring their old team-mate was cautioned.
Bellamy was then struck by a coin and the atmosphere turned nasty. City seemed distracted by the incident as United raced through the gears, seizing the lead.
Giggs had burst down the inside-right channel but lacked support, so he played the ball back to Nani.
The winger sprinted towards the penalty spot where he was disposed by Dedryck Boyata. Carrick leapt in, squeezing the ball to Scholes, whose shot swept from right to left past Given.
As the Stretford End chanted "attack, attack, attack'', United responded, looking for a second but Boyata and Vincent Kompany stood firm.
Still United looked to release Rooney, particularly when Giggs had possession. Still United charged down the flanks, looking to turn City's defence.
Still Webb continued to control tempers superbly.
When Richards and Fletcher gave up on the ball and decided to wrestle with each other, Webb handled it fairly, admonishing both but eschewing bookings.
Fletcher, growing in influence, then made a telling break, racing into the box in pursuit of a pass from Nani, who had neatly controlled Rafael's throw. Fletcher found his path blocked but he managed to lay the ball off to Carrick, whose side-footed shot beat Given as the Stretford End raised the roof. They were soon quietened.
Shortly after Rooney had somehow missed from six yards, Bellamy clipped in a magnificent pass that Tevez, holding off Ferdinand, flicked past Van der Sar.
The game stretching as the minutes grew. Carrick could have settled it but placed his shot wide. Given saved brilliantly from Scholes. Then came Rooney.
Bedlam. (© Daily Telegraph, London)