Paul McGowan scored a second-half winner as Dundee beat Dundee United 2-1 to reach the Betfred Cup quarter-finals.
Championship side Dundee United beat their city rivals on penalties in the group stage after a 1-1 draw at Dens Park in July but they could not repeat the feat on Wednesday.
Faissal El Bakhtaoui opened the scoring for Premiership outfit Dundee with a stunning volley which crashed in off the crossbar on the half-hour mark.
However, the visitors were level within 10 minutes when Billy King slotted home Sam Stanton's cross at the back post.
Neil McCann's troops found the winner midway through the second half, though, when McGowan slotted home from around 18 yards.
In the typically tense derby atmosphere, it was the hosts who began on the front foot and almost drew first blood in the fourth minute. Former Tannadice favourite Scott Allan swung in a corner which seemed to deceive everyone, then bounced off the boot of Marcus Haber four yards out and slid agonisingly past the post.
As United to continue struggle in the air, Haber should have then broken the deadlock but headed narrowly wide from a delightful McGowan chip
The visitors were dealt a blow in the 18th minute when captain Tam Scobbie fell to the ground in a strong tussle with Haber and had to leave the field.
The Dees were in total command but wasted a glorious chance in the 20th minute. A hopeful chip was missed by William Edjenguele, giving El Bakhtatoui the chance to run in on goal, but he rashly skewed his shot wide of the post from 12 yards.
The incessant pressure was finally rewarded on the half-hour with brilliant goal from El Bakhtaoui. Roarie Deacon's cross was headed out by the box by Edjenguelle for the French-Tunisian to pick it up and smack the ball in off the underside of the bar from 20 yards.
It took the timid visitors 36 minutes to create their first chance with in-form Paul McMullen firing over from a Stanton cross. The same player followed with an 18-yard shot which whistled past the post.
The warning signs were there for the hosts and United equalised five minutes from the break with an excellent goal. Stanton powered through the home defence and squared the ball for King to slide in at the far post from six yards.
The second period mirrored the first with Dundee dominating the ball but looking remarkably shaky when the visitors attacked.
With the game becoming evenly balanced, McGowan stepped up to give the Dees a spectacular winner in the 64th minute. Allan chipped in from the left flank for the midfielder to delightfully curl the ball from the edge of the box into the far corner to book a last-16 spot for Neil McCann's side.
ends
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