Match ends, Dundee 2, Dundee United 1.
Dundee came from behind to win the second city derby of the season as Dundee United failed to improve their position at the foot of the table.
James McPake was carried off following a challenge on John Rankin and Blair Spittal scored after a free-kick was awarded against the Dundee captain.
But Eiji Kawashima's mistake let Kane Hemmings score and Nick Ross' deflected shot also beat the debutant goalkeeper.
United's miserable day got worse when midfielder Guy Demel was sent off.
It was only Dundee's second win in this fixture in a decade and, significantly, moves them 16 points clear of their city rivals in the Scottish Premiership table.
Paul Hartley's side had to fight back from the loss of McPake to a suspected dislocated knee early on after he fouled Rankin.
The captain was booked by referee Kevin Clancy before being taken to hospital for treatment.
To make matters worse for the hosts, Spittal scored from the resulting free kick, the midfielder curling a swerving 25-yard effort past a helpless Scott Bain.
However, the Dundee goalkeeper did make a couple of crucial saves after that.
First, he pushed away an acute angled drive from Billy Mckay, set up by another fine bit of play by Spittal with a defence-splitting pass.
Then it was Rankin's turn to be denied by Bain as United played the more incisive football for long spells in the early stages.

It was typical blood and thunder derby fare at a packed Dens Park, the first 45 minutes being particularly eventful, with Kawashima heavily involved.
The Japanese international was cleared to make his debut and, for long spells of the first half, you could see why manager Mixu Paatelainen worked so hard to get him.
He made a couple of decent saves during an opening period dominated by his new team, but four minutes from half time he showed an alarming vulnerability.
The Tannadice team have struggled all season to cope with high balls played into their penalty box and so it proved again.
Nicky Low played a free-kick from deep on top of Kawashima, who made a hash of his punch and Hemmings hooked the loose ball home for his sixth goal in the last three matches.
The goalkeeper claimed in vain for a foul and it was a painful lesson that he cannot expect the sort of protection in Scotland that he has been used to back home or during his spell in Belgium.
Not that his afternoon got any better as Dundee hit the front in 62 minutes with the aid of a deflection as a Ross shot spun off Sean Dillon.
That was enough to wrong foot the unfortunate goalkeeper and his new team start the New Year rooted to the foot of the table and needing a miracle to stay up.
Line-ups
Dundee
Formation 4-4-1-1
- 1BainBooked at 35mins
- 19McGinn
- 5McPakeBooked at 10minsSubstituted forGadzhalovat 15'minutes
- 4KonradBooked at 52mins
- 3Holt
- 30KerrSubstituted forIrvineat 77'minutesBooked at 90mins
- 18McGowan
- 17RossBooked at 45mins
- 8Low
- 29HarkinsSubstituted forThomsonat 71'minutes
- 15Hemmings
Substitutes
- 2Irvine
- 9Loy
- 10Thomson
- 12Mitchell
- 20Calder
- 26Gadzhalov
- 43Skelly
Dundee Utd
Formation 3-5-2
- 1Kawashima
- 2Dillon
- 19GunningSubstituted forMurrayat 77'minutes
- 55DemelBooked at 82mins
- 22Fraser
- 8Rankin
- 12McGowan
- 20Spittal
- 3DixonBooked at 48mins
- 11ErskineSubstituted forBodulat 67'minutes
- 7Mckay
Substitutes
- 4Souttar
- 15Murray
- 16Telfer
- 24Spark
- 28Donaldson
- 30Bodul
- 51Zwick
- Referee:
- Kevin Clancy
- Attendance:
- 11,025
Match Stats
- Possession
- Home53%
- Away47%
- Shots
- Home7
- Away10
- Shots on Target
- Home5
- Away3
- Corners
- Home9
- Away7
- Fouls
- Home18
- Away9
Live Text
Post update
Full Time
Second Half ends, Dundee 2, Dundee United 1.
Booking
Gary Irvine (Dundee) is shown the yellow card for a bad foul.
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Foul by Gary Irvine (Dundee).
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Simon Murray (Dundee United) wins a free kick in the defensive half.
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Corner, Dundee. Conceded by John Rankin.
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Attempt missed. Scott Fraser (Dundee United) left footed shot from outside the box is too high.
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Attempt missed. John Rankin (Dundee United) right footed shot from outside the box is too high.
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Corner, Dundee United. Conceded by Kostadin Gadzhalov.
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Foul by Paul McGowan (Dundee).
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Billy McKay (Dundee United) wins a free kick in the defensive half.
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Nicky Low (Dundee) wins a free kick on the left wing.
Dismissal
Second yellow card to Guy Demel (Dundee United) for a bad foul.
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Foul by Guy Demel (Dundee United).
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Attempt missed. Scott Fraser (Dundee United) left footed shot from outside the box is too high.
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Foul by Paul McGowan (Dundee).
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John Rankin (Dundee United) wins a free kick in the defensive half.
Substitution
Substitution, Dundee. Gary Irvine replaces Cameron Kerr.
Substitution
Substitution, Dundee United. Simon Murray replaces Gavin Gunning.
Post update
Foul by Kevin Thomson (Dundee).