A Graeme Shinnie screamer and Ester Sokler’s first goal for the club were enough to sink spirited Ross County and keep alive Aberdeen hopes of ending a decade-long wait to lift silverware.
Barry Robson’s rejuvenated Dons made it back-to-back victories over the Highland side, who served up gutsy resistance and fight after Jack Baldwin’s disastrous 13th minute red card.
County won and scored a late penalty, with Kyle Turner dragging the game back to 2-1, but the semi-final trip to Hampden Park will be made by the red contingent after a rain-soaked victory at the Global Energy Stadium.
Not since Inverness Caley Thistle were beaten on penalties in the 2013/14 League Cup final have the Pittodrie side savoured trophy success.
Out of sorts through August and much of September, Aberdeen looked re-energised and awash with confidence after a valiant showing away to Eintracht Frankfurt and Sunday’s 4-0 victory over County.
Dons manager Barry Robson refused to get carried away with the prospect of a Hampden return.
“There’s a lot of new players in the building and we all know that. We haven’t performed as well as we could have in games but we’ve performed really well in other games,” Robson said.
“I think over the last week we’ve performed well but we’re at the start of the league and we haven’t achieved anything. We’re not where we want to be.
“The semi-final against Hibs is a good tie for us. We’re at Hampden, we’re still in the fight in the group stages of Europe, the League Cup and we want to push up the league.
“I’m not going to think too far ahead. Let’s try to see who performs as well as they can as there’s a long way to go before then.
Reflecting on Shinnie’s stunning moment, he added: “That’s why Graeme is the captain. He performed really well.”
Inside four minutes, Connor Barron’s sidefoot forward released Duk to the left but his attempt was easily held by keeper Ross Laidlaw.
The away support then erupted four minutes later after a quite stunning opener from Graeme Shinnie.
Stefan Gartenmann’s long throw from the right of the box found a clutch of players rising to meet it in the air, with County’s Will Nightingale nodding it away.
It spun to Shinnie’s left, though, and the Dons’ skipper’s response was breathtaking.
Meeting it sweetly on the volley at the edge of the penalty area with a flash of his left foot, the ball rocketed high into the top left corner of the net off the underside of the bar.
It then went from bad to worse for the Highland side inside 13 minutes as Jack Baldwin took a straight red card for bringing Duk crashing as the Cape Verde international raced onto a defence-splitting pass.
Hayes could only hit the wall with the free-kick, but the Staggies were in trouble.
The away side quickly asserted control with the one-man advantage.
It might easily have been 2-0 after 24 minutes as Miovski surged clear on the right and rolled a simple pass across to Duk, who slipped and fell at the vital moment.
County did enjoy little spells of pressure, but were toiling to seriously threaten Kelle Roos in front of the big away crowd.
Towards half-time, Miovski turned and deftly chipped Laidlaw from inside the penalty area, but saw the ball nestle on top of the net.
A flourish from the hosts three minutes before the break saw Josh Sims deliver a fine ball across the danger area and Yan Dhanda force a desperate block, but the lead stood.
Sims and Dhanda seemed to offer County’s best hope of a route back as the second half unfolded, with both able to hold and move the ball effectively.
County, though, lived in constant danger of the Dons grasping a killer second and after an early second half spell of possession and pressure, Duk slipped Hayes into space in the box and Laidlaw had to be sharp to save down low.
The longer the lead remained at a single goal, the more hope grew in the home camp.
Their luck was in after 68 minutes.
Shinnie sped onto the ball on the left, cutting into the penalty area and it looked like County full-back James Brown had clearly chopped him down. Referee John Beaton said no.
County’s best performer Sims had to exit by stretcher after being left writhing in agony by substitute Ryan Duncan’s late challenge.
The killer blow finally arrived with 10 minutes remaining.
County’s hopes rose with a free-kick deep right, but the Dons tore away on the counter, with substitute Leighton Clarkson’s run and superb ball across from the right stabbed home on the run by fellow replacement Ester Sokler.
It was the Slovenian’s first goal for the club he joined in the summer.
Remarkably, County then won an 82nd minute penalty when Aberdeen’s Slobodan Rubezic took down substitute Alex Samuel.
Kyle Turner thumped the spot-kick high into the top right corner to resurrect home hopes. County, with flawless workrate and commitment, forced a spate of late corners to no avail.
Home manager Malky Mackay was unhappy with some of the refereeing decisions, particularly the lack of punishment after Ryan Duncan’s unpunished late lunge at Sims.
“I'm really disappointed,” Mackay said. “I think if VAR had been operational the sending off would be looked at.
“I think with ten minutes to go Aberdeen were trying to shore up at the back.
“I’m disappointing but really proud of the players.
“There seemed to be a lot of bookings and then a couple of bizarre ones after that
“Josh is away to hospital with his leg split wide open - I don't know why there is not a booking on Ryan Duncan with that.
“We are just looking for a bit of consistency and a little bit of dialogue. “
