Wayne Rooney's 91st-minute header secured a 3-1 victory for Manchester United over rivals City at Old Trafford and carried the holders through to a League Cup final meeting with Aston Villa.
The England forward struck with a close range header from a Ryan Giggs cross following a well-worked short corner and clinched a 4-3 aggregate semi-final victory, denying City what would have been a place in their first major final for 29 years.
On an evening of high drama at Old Trafford, former United forward Carlos Tevez -- scorer of both goals in City's 2-1 first leg victory last week -- was again prominent as his 75th minute goal tied the aggregate scores at 3-3.
After a goalless first half, Rooney sent Giggs racing clear in the 51st minute and, after City appeared to have halted the attack, Michael Carrick's pass found veteran midfielder Paul Scholes who finished clinically from a dozen yards.
In the 70th minute, the tie looked decided after Darren Fletcher laid a Nani pass into the path of Carrick who scored with a precision 'pass' into the corner of the City goal.
But Tevez struck five minutes later, flicking the ball powerfully into the home goal from eight yards after United failed to deal with Craig Bellamy's cross.
The build-up to the second leg had been intense; the feud between Tevez and Gary Neville, the FA warning both clubs about their behaviour, City's chief exec Garry Cook appearing in a televised rally in which he gloated to his club's fans that they would become "the biggest and the best in the world."
There had also been a major operation by Great Manchester Police, who made a number of pre-match raids around the region in an effort to avoid the crowd trouble that had marred the first leg.
Against this backdrop, the game started at a frenetic pace with United playing Rooney as a solitary striker ahead of a five-man midfield.
Nani, so impressive in helping Rooney score four in the weekend league victory over Hull, forced young City defender Dedryck Boyata to make a superb defending header with Rooney poised to connect.
Tevez was being jeered by home support every time he touched the ball and his former fans were far from impressed when he went down heavily after Rio Ferdinand appeared to accidentally catch the Argentine under the chin with his trailing arm.
But City, full of pace and daring on the counter-attack, looked capable of adding to their slender first leg advantage. In the 22nd minute, Shaun Wright-Phillips landed a perfect cross for Bellamy whose effort was well kept out by Edwin van der Sar before Tevez tested the keeper with a diving header.
United responded with Giggs' latching onto Fletcher's neat lay-off and drawing a fine save from Given before the Irish keeper was again alert in keeping out Giggs' dangerous cross after a rare slip by Boyata.
If anything, the second half opened in even more intense fashion than the first with defender Micah Richards being allowed to advance to the edge of the United area before testing van der Sar.
Tevez was booked for a nasty hack at Rafael, joining Scholes in the book for a first half foul on Wright-Phillips and the mood darkened further when Bellamy appeared to be hit by a coin thrown by United fans as he took a City corner. A minute later, Scholes levelled the aggregate score and, shortly after, had a hand in another promising attack which ended with a goalmouth scramble and Fletcher seeing his shot deflected to safety.
Boyata had to defend heroically, again, to keep out a Nani cross while Carrick did well in flicking over a threatening Richards header but, after Carrick had doubled United's lead, a miss by Rooney looked in danger of becoming the game's turning point.
The moment came in the 72nd minute from Patrice Evra's left-wing cross which Rooney, off-balance, directed wide. Three minutes later, Tevez equalised the aggregate score and United were back at square one.
A late Carrick shot and weak header from substitute Emmaneul Adebayor both failed to threaten the keepers and the semi-final appeared to be heading for extra-time until the late drama.