Aberdeen reached the Scottish Cup final for the first time in 17 years after overcoming holders Hibernian.
Adam Rooney pounced on a defensive mix-up to put the Dons ahead 12 seconds after kick-off and Ryan Christie's free-kick doubled their lead.
Substitute Grant Holt headed Hibs back into the game before half-time and the striker set up Dylan McGeouch to level.
But Jonny Hayes's shot deflected off Darren McGregor and beat Ofir Marciano for Aberdeen's winner.
Manager Derek McInnes, who won the League Cup with the Dons in 2014, now has a cup final against either Celtic or Rangers on 27 May to prepare for, with the latter two sides meeting on Sunday.
And Aberdeen, currently second in the Premiership, will attempt to end a 27-year wait to win the Scottish Cup.
Perfect start for Dons
Their start to the match was as perfect as it was calamitous for Hibs.
A mistake McGregor allowed in Rooney, who wasted no time in storming into the penalty area to slot home. The Aberdeen fans could barely believe it. It was a moment to make everyone of a Hibs persuasion sick to the stomach.
The lightning goal helped as Aberdeen looked much the more assured side in the early stages. Hibs in contrast looked ill-at-ease as they struggled to find any sort of foothold.
Hibs looked groggier still as they went 2-0 down. Christie lined up a free-kick wide on the right on the edge of the box and the Hibs defence lined up expecting a cross.
Instead the on-loan Celtic player went straight for goal, whipping the ball in at pace and beating Marciano at his near post. It was a superb strike from Christie - selected ahead of Niall McGinn - but it was a goal the Hibs goalkeeper and defensive wall simply should not have conceded.
Holt leads recover for holders Hibs
Having seen his side fail to get any traction Hibs manager Neil Lennon realised something had to change tactically. A visibly disappointed Fraser Fyvie was hooked, replaced by the burly presence of striker Holt as Hibs changed tack.
It paid immediate dividends. A great run and cross from Martin Boyle saw the ball swung up to the back post and there was Holt to steer a header home with his first touch and give Hibs a vital lifeline.Holt netted his fifth goal of the season and his second in the Scottish Cup
The 36-year-old's introduction completely changed the dynamic. Suddenly the cup holders were winning the ball in the air and disrupting Aberdeen's flow as the match became a much more even affair.
Hibs drew level with a moment of real quality, with Holt again involved. McGeouch swept forward and played the ball to the feet of Holt, who flicked the ball back to the midfielder and McGeouch kept this composure to fire low past Joe Lewis.
It was a huge blow for Aberdeen who had earlier gone close through Shay Logan and switched to a back three, with Anthony O'Connor replacing Christie.
Suddenly the tactical game of chess became more complex, McInnes now the manager with the dilemma and Lennon in charge of the side with the wind in it's sails.
Reds have the final say
McGinn came on in place of Mark Reynolds as the Dons shuffled the pack again, but as the match moved towards its final quarter.
In the end, a stroke of luck gave Aberdeen the edge. Hayes did well to make space for a shot from long range, and the ball appeared to pose no real threat to Marciano's goal until it took a deflection off the unfortunate McGregor and trundled into the net.
Hibs had one last roll of the dice as they tried to hold on to the cup from a corner. Keeper Marciano came up for a stoppage-time corner and headed towards goal, but his counterpart Lewis held to ensure Aberdeen progressed to the final.