Johnny Russell blotted his copybook with a red card after his quickfire double helped Dundee Utd win the first competitive city derby in seven years.
Goalkeeper Radoslaw Cierzniak denied Nicky Riley as Dundee pressed early on, but a Rab Douglas mistake allowed Gavin Gunning to head in on 14 minutes.
Russell's deflected effort lifted over the Dundee goalkeeper after 35 minutes.
He fired in a stunner three minutes later but was sent off with Dundee's Stephen O'Donnell on 72 minutes.
That did nothing to temper the joy of most of a 14,000 capacity crowd at Tannadice that witnessed United go top of the Scottish Premier League with a game in hand.
Russell celebrates as he scores against Dundee before being sent off
That game is away to Celtic, but for now Peter Houston's side are the pacesetters and the most likely to mount a challenge to the reigning champions in the absence of financially ruined Rangers.
United, who beat Hibernian impressively in their opening SPL fixture, quickly applied pressure as they looked to recover from their 5-0 hammering by Dinamo Moscow in the Europa League qualifiers in front of a crowd that had the stadium - and the whole city - rocking.
The home side were without in-form winger Gary Mackay-Steven through injury, but only a desperate block on the edge of the penalty box prevented his replacement, Michael Gardyne, from finding the target with a powerful early drive.
Dundee manager Barry Smith had made one change and it was a conservative one, with Riley replacing striker Mark Stewart after the midfielder's return from injury.
However, Riley was quickly involved in the United penalty box and should have opened the scoring only to have two efforts parried by Cierzniak from point-blank range before the ball was scrambled for a corner.
That instilled some uncertainty in a United defence in which Sean Dillon was preferred to Brian McLean, but it was United who took the lead.
Jon Daly had scored a hat-trick in a pre-season friendly between the sides and the Dundee defence appeared to be concentrating on blunting the big striker as Willo Flood's free-kick was misjudged by Douglas and Gunning headed in at the back post.
United were catching Dundee on the break and, when Daly threaded in Russell, the former Scotland Under-21 striker's low drive took a deflection off the despairing Davide Grassi, flew over Douglas and spun into the far corner of the net.
Dundee will feel aggrieved about Russell's second, which immediately followed an incident at the other end for which they should have been awarded a penalty, Riley shoved by Richie Ryan on the edge of the penalty box.
Instead, a Ryan Conroy free-kick struck the defensive wall, Russell broke into the Dundee half and fired a blistering left-foot drive into the top corner of the net.
Douglas made some amends for his early flap after the break by pushing clear a powerful Ryan drive and then saving a downward Daly header on the goal-line after Flood followed up by floating a cross to the back post.
Cierzniak dived low to save a fine drive by Conroy, but the biggest talking point of a feisty second half was the double red card, with Russell perhaps unlucky to be dismissed for a half-hearted kick out at O'Donnell after the midfielder's late challenge.
While United are flying high, defeat leaves Dundee at the foot of the table looking for their first win - and first goal - back in the top flight.
Corner taken right-footed by Ryan Conroy from the left by-line, Jon Daly manages to make a clearance.
Substitution Graham Webster comes on in place of Nicky Riley.
Substitution Brian McLean is brought on as a substitute for Gavin Gunning.
Stuart Armstrong fouled by Iain Davidson, the ref awards a free kick. Barry Douglas takes the direct free kick.
Booking Booking for Radoslaw Cierzniak for unsporting behaviour.
Dismissal Johnny Russell receives a red card for violent conduct.
Dismissal The referee shows Stephen O'Donnell a red card.
The ball is swung over by Keith Watson, Kyle Benedictus makes a clearance.
Substitution Stuart Armstrong comes on in place of Michael Gardyne.
Johnny Russell crosses the ball.
Johnny Russell is ruled offside. Rab Douglas takes the free kick.
Substitution Martin Boyle comes on in place of James McAlister.
Willo Flood crosses the ball from the free kick right-footed from left wing, clearance by Gary Irvine.
Booking The referee books Kyle Benedictus for unsporting behaviour.
Michael Gardyne fouled by Kyle Benedictus, the ref awards a free kick.
Free kick awarded for a foul by Gavin Gunning on Nicky Riley. Stephen O'Donnell takes the free kick.
Shot from just outside the box by John Rankin goes over the crossbar.
Foul by Gavin Gunning on Nicky Riley, free kick awarded. Stephen O'Donnell crosses the ball from the free kick right-footed from left channel.
Substitution Mark Stewart is brought on as a substitute for John Baird.
Corner taken right-footed by Willo Flood, Rab Douglas makes a save.
John Baird is flagged offside by the assistant referee. Indirect free kick taken by Radoslaw Cierzniak.
The ball is crossed by John Baird, Ryan Conroy takes a shot. Save by Radoslaw Cierzniak.
Jon Daly challenges Davide Grassi unfairly and gives away a free kick. Stephen O'Donnell takes the free kick.
Outswinging corner taken by Willo Flood from the right by-line, Gavin Gunning has a headed effort at goal from deep inside the area missing to the left of the target.
Free kick awarded for an unfair challenge on Richie Ryan by Iain Davidson. Keith Watson restarts play with the free kick.
Jon Daly takes a shot. Fantastic save by Rab Douglas.
Richie Ryan takes a shot. Rab Douglas makes a brilliant save.
The free kick is swung in right-footed by Jon Daly, clearance made by Davide Grassi. Corner taken by Willo Flood, Gary Irvine makes a clearance.
Booking Nicky Riley goes into the book.
Nicky Riley gives away a free kick for an unfair challenge on Michael Gardyne.
Outswinging corner taken right-footed by Willo Flood from the right by-line, Stephen O'Donnell makes a clearance.
The referee gets the second half started.
45:00 +1:05 Half time
Half Time The ref blows to end the first period.
Jon Daly challenges Iain Davidson unfairly and gives away a free kick. Matthew Lockwood restarts play with the free kick.
Michael Gardyne is flagged offside by the assistant referee. Indirect free kick taken by Rab Douglas.
Assist by Barry Douglas.
37:45 Goal scored
Goal! - Johnny Russell - Dundee U 3 - 0 Dundee A goal is scored by Johnny Russell from just outside the area to the top right corner of the goal. Dundee Utd 3-0 Dundee.
Richie Ryan challenges John Baird unfairly and gives away a free kick. John Baird has a direct shot on goal from the free kick.
John Rankin provided the assist for the goal.
34:02 Goal scored
Goal! - Johnny Russell - Dundee U 2 - 0 Dundee Goal scored by Johnny Russell from close in to the bottom right corner of the goal. Dundee Utd 2-0 Dundee.
Jon Daly crosses the ball, clearance by Gary Irvine. Gary Irvine fouled by Jon Daly, the ref awards a free kick. Rab Douglas takes the free kick.
Effort from outside the penalty box by Ryan Conroy goes wide right of the target.
John Baird is flagged offside by the assistant referee. Indirect free kick taken by Gavin Gunning.
Sean Dillon fouled by John Baird, the ref awards a free kick. Direct free kick taken by Willo Flood.
John Rankin has an effort at goal from deep inside the area missing to the right of the goal.
Jon Daly has an effort at goal from 12 yards. Davide Grassi gets a block in. Corner taken right-footed by Willo Flood from the right by-line, clearance made by Gary Irvine.
The ball is swung over by John Baird.
Gary Irvine takes the free kick.
Booking Michael Gardyne is cautioned by the ref for unsporting behaviour.
Free kick awarded for a foul by Michael Gardyne on Stephen O'Donnell.
Iain Davidson gives away a free kick for an unfair challenge on Sean Dillon. Radoslaw Cierzniak takes the free kick.
The ball is sent over by Keith Watson.
Assist on the goal came from Willo Flood.
13:21 Goal scored
Goal! - Gavin Gunning - Dundee U 1 - 0 Dundee Gavin Gunning scores a headed goal from close in. Dundee Utd 1-0 Dundee.
Free kick awarded for a foul by Kyle Benedictus on Johnny Russell. Willo Flood sends in a cross,
Free kick awarded for an unfair challenge on John Baird by Barry Douglas. Ryan Conroy delivers the ball from the free kick right-footed from right wing, clearance by Jon Daly. Outswinging corner taken by Ryan Conroy, clearance by Sean Dillon.
Keith Watson produces a cross.
Nicky Riley takes a shot. Blocked by Nicky Riley. Nicky Riley takes a shot. Radoslaw Cierzniak makes a save. Outswinging corner taken right-footed by Stephen O'Donnell, Header on goal by Kyle Benedictus from inside the box goes harmlessly over the target.
Michael Gardyne takes a shot. Kyle Benedictus gets a block in.
Inswinging corner taken by Willo Flood, save made by Rab Douglas. The referee blows for offside. Free kick taken by Rab Douglas.
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