Craig Bellamy came back to haunt his former club Manchester City as Liverpool booked their first Wembley appearance for 16 years after a dramatic 2-2 draw with the Premier League leaders in the semi-final second leg of the League Cup.
Leading 1-0 from the first leg, Liverpool were undone by Nigel De Jong's spectacular 31st minute long-range finish before skipper Steven Gerrard restored their aggregate lead with a controverial 41st minute penalty.
But City striker Edin Dzeko made it 2-2 on aggregate after scoring from close range midway through the second half before Bellamy's well executed 74th minute finish sealed a breathtaking tie in Liverpool's favour, the Mereyside club advancing 3-2 on aggregate.
Bellamy scored 12 goals in 40 top-flight games for City before joining Liverpool for a second spell five months ago on a free transfer after spending the whole of last season on loan at Cardiff.
Ironically, it is Cardiff who stand between Liverpool and their first trophy for six years.
Kenny Dalglish's side will now meet the Championship club in the League Cup final on February 26 - Liverpool's first final at the famous stadium since losing 1-0 to Manchester United in the 1996 FA Cup final.
A dramatic evening had started with City opting not to appeal against Mario Balotelli's four-match suspension for violent conduct in last Sunday's 3-2 victory over Tottenham.
Mancini surprised everyone by starting without Sergio Aguero and James Milner in a game City had to win if last season's FA Cup winners were to secure a second cup final appearance at Wembley in nine months.
It was Liverpool who made the better start with Joe Hart forced to save with his foot to deny Jose Enrique in the fifth minute following a poor clearance by Aleksander Kolarov.
Boasting a slender first leg advantage thanks to Gerrard's 13th minute penalty, the lively hosts looked in the mood to kill the tie off early.
Charlie Adam forced England keeper Hart into a full-length stop after letting fly from 25-yards before Bellamy was denied after turning City defender Stefan Savic and darting into the area.
Daniel Agger produced a fine clearance while under pressure from Dzeko after Kolarov's 16th minute cross before the visitors took the lead against the run of play through De Jong.
The former Ajax player has struggled to cement a regular starting place this season. But de Jong had his manager celebrating on the touchline after finding the net with a swerving shot from 30-yards after Liverpool had failed to close him down.
But City's lead lasted just nine minutes as Liverpool levelled before half-time in controversial cirumstances, Gerrard burying the ball beyond Hart after Micah Richards was harshly adjudged to have handled Agger's shot.
Although television replays showed the defender did touch the ball after it bounced from his shin, it was not intentional and City's players argued long and hard but to no avail.
Leading 2-1 on aggregate, Liverpool went in search of the goal that would kill the tie off and confirm their place at Wembley.
Dirk Kuyt fired straight at Hart from a good position in the 48th minute before the City keeper produced another fine save to deny Martin Skrtel from close range five minutes later.
Stewart Downing was the next to be frustrated by City's stopper after Kuyt had whipped in a cross while Bellamy mis-kicked in front of goal in the 62nd minute.
And the squandered opportunities were to prove costly as Dzeko hauled City back on the level terms on aggregate and into a 2-1 lead on the night.
Mancini, who had sent on Aguero at the start of the second half, showed little emotion as Dzeko side-footed home from three-yards after Kolarov's fine cross.
But once again City failed to defend their lead as Bellamy exchanged a one-two with Johnson inside the City box before placing a low curling shot beyond the outstretched hands of Hart.