FOR three days Dundee had been presented as city united behind a common cause, the place that delivered Scotland's most resounding Yes vote in the referendum.

Social justice weighs heavily on Tayside minds. Inequality on a football pitch? That doesn't bother everyone. Dundee United delivered a murderous rout in their first derby of the season and how their supporters lorded it over the less well off.

Once they had a lead thanks to Mario Bilate's penalty midway through a scrappy first half, United took control. They had too much pace and menace when they went at Dundee and when they fired set-pieces into the goalmouth Paul Hartley's team, unusually, were all over the place. United are top of the SPFL Premiership.

Their very fine start to the season has been under the radar because of that bruising 6-1 defeat at Celtic, when they defended horribly. Here they gave Dundee very little and were ruthless with their own chances. When they're in full flow United are quite a sight. That wasn't really the case here, but they still delivered a margin of victory all the more commendable for the fact their best forward, Nadir Ciftci, was suspended.

Not since November 2004 have United lost a derby. This was the seventh since then and Dundee have another crack at their neighbours in the League Cup on Wednesday. Hartley has fashioned an organised, spirited team which was unbeaten in all eight games before yesterday, but they were inadequate at both ends yesterday.

By the time Thomas Konrad was sent off in the dying minutes all the damage had been done. It is a defeat they can shake off, given the excellent start to the season which has them in the top six and 10 points clear of Ross County.

It was a predictably hard-fought, untidy battle. The stands howled for free kicks and penalties at every challenge, and there were dozens of those. Through the first half it was impossible for either side to establish any sort of flow or rhythm, such was the intensity of the tackling and competitiveness all round. Scrambled and hectic, with challenges flying in and players charging, colliding and blocking each other, it was a sustained assault on the eyes and ears.

Out of this scrappy, scruffy mess of a game, United scored. What a performance Paul Paton delivered, exemplified by the crunching tackle on Jim McAlister which won the ball for Gary Mackay-Steven. The quicksilver, slip of a winger ran at Konrad and the danger was obvious.

Konrad unwisely let the United man enter the penalty area before making an uncomfortable, awkward challenge. His leg went out and Mackay-Steven went down, earning a penalty which had his every touch of the ball booed by most of Dens Park for the rest of the afternoon. Referee Steven McLean wore a red shirt which wasn't easily distinguishable from United's colours: the Dundee fans howled that he was the 12th man. Still, the penalty was the right call and Bilate tucked it away.

Dundee huffed and puffed. Only towards half-time was there anything to show for their graft. A dribble and a chip across the box from Gary Harkins gave Philip Roberts a chance which he rasped into the side netting. Greg Stewart's free kick into the box was glanced on to the roof of the net by McAlister. At that point United hadn't created a decent chance before their goal or after it.

The roof fell in on Dundee as United opened up with two goals in six minutes. Ryan Dow had been quiet, working unobtrusively behind Bilate in United's 4-4-1-1. That changed when Jon Rankin pickpocketed the ball off McAlister and gave it to him in midfield. Dow motored into the box and cleverly rifled a crisp shot into the bottom corner.

That was hard for Dundee to take and United's third was too much for some. Paton's free kick into the box was converted so, so easily by Callum Morris's firm downward header. The home stands began to thin out.

The cruelty intensified. Paul McGowan tripped Stuart Armstrong in the corner: another free kick, another Paton delivery into the goalmouth, another headed goal. Keith Watson got well clear of Stewart at the back post to force the ball past goalkeeper Kyle Letheren.

Dundee had unravelled. Konrad, booked when conceding the penalty, got a red card for cutting down Scott Smith in the 89th minute. The best goal of the day was Dundee's when Stewart moved the ball on to his right foot and swept home a firm shot from the edge of the box.

It deserved better than what it inevitably received: a collective shrug of the shoulders.