First-half goals from Brian McLean and Gary Mackay-Steven helped Dundee United claim their third derby victory this season over neighbours Dundee and a place in the Scottish Cup semi-finals.
The Dens Park side gave a better showing than they had in the first two City of Discovery derbies in the SPL this season and Jim McAlister drew them level for a time, claiming the first goal in the fixture for the Dark Blues this term.
Dens interim boss John Brown made three changes to the side that snatched a point at home to St Johnstone on Tuesday, with inexperienced defensive duo Kyle Benedictus and Declan Gallagher missing out while midfielder Gary Harkins was cup-tied. Davide Grassi, Brian Easton and Steven Milne replaced the trio.
Terrors boss Jackie McNamara had to do without star striker Johnny Russell for his first derby in charge of the Tannadice outfit, with Stuart Armstrong starting in place of the 22-year-old forward.
The visitors opened up the scoring with only 10 minutes gone as McLean got in behind Lewis Toshney to get on the end of a Barry Douglas free kick from the right wing and power a header beyond Rab Douglas in the Dark Blues goal.
But eight minutes later Dens Park sparked into life as the SPL's bottom side got their first derby goal of this season. John Baird crossed from the right-hand side of the box for McAlister to smash the ball past Radoslaw Cierzniak and level the cup tie.
Barely a minute later Dundee thought they should have had a penalty as Nicky Riley went down inside the box under a challenge from Willo Flood, but instead of awarding the spot kick, referee Iain Brines booked the Dark Blues midfielder.
With just over 10 minutes left in the first half the Tannadice side retook the lead. Armstrong played a defence-splitting pass through the middle of the Dundee backline for Mackay-Steven to smash home from the edge of the area.
The visitors almost handed their hosts an equaliser within two minutes of the restart as McLean and Cierzniak got into a mix-up, with the defender attempting to head a long ball back to his keeper only to find that the Polish stopper had raced from his line. Fortunately for United, the ball drifted out for a corner.
Dundee continued to push forward in search of a leveller that would send the tie back down the road to Tannadice and a replay, but Brown's side continually struggled to get past a solid Terrors defence and when they did, Cierzniak was more than equal to anything thrown at him.
McNamara's side managed to hang on through the closing stages of the game as his opposite number Brown brought on the cavalry, with strikers Mark Stewart and Colin Nish both coming off the bench in a desperate attempt to snatch a replay.
But they couldn't find a way past the visitors' defence, and the Terrors secured a place in the semi-finals and took another step towards emulating the side that won the tournament three years ago.