Paul Scholes was sent off as Manchester City ended Manchester United's treble bid by booking their first FA Cup final appearance since 1981.
Man-of-the-match Yaya Toure was City's second-half matchwinner, seizing on a catastrophic blunder by Michael Carrick before finishing smartly past Edwin van der Sar.
Roberto Mancini's men just about deserved it too after surviving an early pummelling and two glorious opportunities for Dimitar Berbatov.
Their task was made easier when Scholes departed though, dismissed for a thigh-high studs-first lunge on Pablo Zabaleta.
It means there will be no repeat of 1999 for United, who must concentrate on their bid for glory in the Premier League and Champions League.
City, watched by chairman Khaldoon al-Mubarak, have the chance to "change history" as Mancini has demanded, and will return to Wembley on May 14 to face either Bolton or Stoke looking to collect their first trophy in 35 years.
Unfortunately, firebrand Mario Balotelli threatened to put a dampener on celebrations when he unwisely rejoiced in front of the United fans, triggering a shoving match with Anderson and an angry reaction from Rio Ferdinand - who also squared up to City coach David Platt.
The current Premier League leaders took a stranglehold on the contest as soon as the polite opening exchanges had been completed.
That the Red Devils did not go in front during that prolonged period of dominance was due to a magnificent save from Joe Hart and a moment to forget for Berbatov.
Challenged to respond to the startling emergence of Javier Hernandez by his manager, the City goal first opened up for Berbatov when Carrick intercepted a Gareth Barry pass and began a fabulous one-touch move that involved Scholes and Park Ji-sung.
The Bulgarian found himself one-on-one with the outstanding Hart and went for the bottom corner. The England goalkeeper won.
United quickly retrieved possession and when Nani gave Zabaleta the slip, his low cross invited the close range finish. However, the man who had found the net for United 22 times this season scooped over from inside the six-yard box.
Nemanja Vidic turned an Antonio Valencia corner wide and Berbatov looped a far-post header just over as City's defence continued to creak without snapping completely.
It was half an hour before City managed to push their opponents back and make them do some defending of their own.
Although he had been close to non-existent after being handed the job of filling the massive gap created by Carlos Tevez's hamstring injury, Balotelli eventually burst into life, letting fly with a rasping 30-yard drive Van der Sar touched over.
Had Balotelli got on the end of Adam Johnson's corner shortly afterwards, United would have been in trouble.
As it was, the ball floated over the Italian to Joleon Lescott, who could not keep his first-time volley down.
Blues skipper Vincent Kompany curled a 20-yard effort just wide as half-time approached, then Balotelli failed to keep a near-post effort on target immediately after the break.
However, they were not about to let United off the hook in the manner Berbatov had done earlier.
Toure needed the assistance of a woeful attempt to find Scholes by Carrick. But once the Ivorian had been invited into the Red Devils' box, he finished in style, beating Van der Sar with a low shot through the veteran Dutchman's legs.
Now it was United's turn to wobble, just as they did in the Carling Cup semi-final 15 months ago.
On that occasion, Mancini failed to seize the initiative, settling for what he had in the first leg and watching his team swept aside in the second.
They didn't have Toure then, or David Silva.
It was the Spain star who crossed to present Lescott with another golden opportunity, which the England defender headed wide.
Given Ferguson compared the striker to Gary Lineker yesterday, it was not a surprise Javier Hernandez was asked to complete a salvage mission.
When the Mexican was introduced, United already had the free-kick that Hart pushed onto the bar as Nani went for the roof of City's net.
The comeback powers of Ferguson's team are the stuff of legend. Scholes' awful challenge on Zabaleta presented a challenge even they were up against it.
Carrick tried to atone for his blunder with a curling shot and Park attempted to steer a header towards goal but on neither occasion was Hart troubled to make the save.
As valiant as United's 10-men fought, City came closer to increasing their lead through Balotelli at the end.
It didn't matter and now the door to glory stands ajar for Mancini's men.