Dundee United came roaring back at Tynecastle to set up a meeting with Rangers in the CIS Insurance Cup final.
United ran out comfortable winners at Tynecastle
Andrew Considine shot Aberdeen in front only for Darren Dods to nod United back on level terms before half time.
A Christian Kalvenes header put United in front and Craig Conway slid in a fine solo goal from an acute angle.
Dons striker Lee Miller was sent off for two bookings and a terrible defensive mix-up gifted Morgaro Gomis a simple finish to wrap up the victory.
The Tannadice side were by far the better team throughout and responded with an impressive display after going a goal down.
But Aberdeen were the architects of their own downfall, with some calamitous defending.
United looked the more menacing side in the opening stages but it was the Dons who opened the scoring after 18 minutes.
Zander Diamond got his head to a Barry Nicholson corner and forced a save from Lukasz Zaluska but Considine was on hand to bundle the ball into the net from close range.
United were level four minutes later when Dods glanced in an expertly whipped free-kick from Kalvenes, making his first appearance since he picked up an injury in November.
With the game raging on at a rapid rate of knots Dons skipper Scott Severin fired a powerful long-range effort a yard over the crossbar.
Central defender Dods came close to a second goal on 38 minutes when he headed a Conway cross narrowly wide, with Lee Wilkie throwing himself at the speeding ball and only inches away from diverting it in.
Kalvenes was one of many top performers for United
The second half began in scrappy style, with play punctuated by a series of niggling fouls.
Neither goalkeeper had much to do until Aberdeen's Jamie Langfield made a hash of pass-back, conceding a corner.
And that was to prove costly, as Kalvenes threw himself at Conway's delivery to power home an impressive header.
United increased their lead soon after, with Conway taking advantage of some ponderous defending to skip round Langfield and squeeze a shot in from a tight angle.
Nicholson fluffed a great chance to reduce the deficit when his weak header was gathered by Zaluska.
The Dons' cause was further hampered when striker Miller was sent off after picking up a second yellow card.
Despite being a man down, Aberdeen continued to look dangerous and Zaluska had to make a vital block as Darren Mackie pounced on a poor pass-back from Willo Flood.
However, Jimmy Calderwood's side were again undone by sloppy play as Gomis knocked in United's fourth goal on 77 minutes.
Severin put Langfield under pressure with a short back-pass and the keeper was left red-faced again as the United midfielder nipped in to tuck the ball into an empty net.
Aberdeen: Langfield, McNamara (Bus 79), Diamond, Severin, Considine (Aluko 67), Young, Nicholson, Josh Walker, Mackie, Miller, Foster. Subs Not Used: Soutar, Maguire, Maybury.
Sent Off: Miller (68).
Booked: Miller, Josh Walker, Mackie.
Goal: Considine 19.
Dundee Utd: Zaluska, Flood (Dillon 79), Dods, Wilkie, Kalvenes, David Robertson, Kerr, Gomis (Buaben 79), Conway, De Vries, Hunt. Subs Not Used: McLean, Kenneth, Odhiambo.
Booked: Kerr, De Vries, Dods.
Goals: Dods 23, Kalvenes 60, Conway 65, Gomis 77.
Ref: I Brines