Craig Wighton was the hero for Arbroath as he scored the goal which inflicted Dundee United’s first home defeat since July.
The Tangerines hadn’t lost at Tannadice since going down to East Fife in the early stages of the Betfred Cup last summer and were unbeaten on their own patch all season in the Championship.
However, former Dundee man Wighton’s effort on 26 minutes ended that streak, and the Terrors 13-match unbeaten league run in the process, as the runaway second-tier leaders were stunned by the part-timers.
United showed two changes from the 4-2 defeat at Hibs on Tuesday night with Adrian Sporle and Osman Sow checking in for Ian Harkes and Louis Appere.
The Terrors started on the front foot, with Calum Butcher the first to fire an effort goalwards on five minutes. However, he saw his 25-yard drive deflected behind for a corner.
On 12 minutes, Liam Smith managed to get to the byline before swinging in a cross Sow was inches away from getting on the end of.
However, that was the big Swede’s final involvement of the afternoon as he had to be stretched off after turning his ankle on 14 minutes. Declan Glass came on in his place.
That didn’t halt United’s attacking verve, though, as Peter Pawlett came close to giving them the lead on 23 minutes.
Slipped in by Lawrence Shankland, his left-foot shot was smartly foiled by away goalkeeper Derek Gaston.
On 26 minutes, against the run of play, Arbroath seized the initiative with Colin Hamilton and Wighton linking up to open the scoring.
Haring down the left, Hamilton fed the ex-Dundee hero who slotted home at the near post through Benjamin Siegrist’s legs.
Eight minutes from the half, sub Glass forced Gaston into another good save with the Red Lichties’ goalie tipping over his 25-yard effort.
David Gold scooped over on the stroke of half time as Dick Campbell’s men threatened to make it 2-0. And that was that for the first period with all the Tangerines’ pressure counting for nothing.
United’s onslaught continued into the second 45 with Shankland curling an effort powerfully over the bar on 47 minutes.
Pawlett, again, came close on 51 minutes but the equaliser was seemingly not forthcoming.
After coming off worse in a clash of heads with Finnish midfielder Miko Virtanen, Glass had to be replaced on 62 minutes by Harkes.
And the American playmaker was involved straightaway, guiding a header towards goal which was comfortably saved by Gaston.
Ten minutes from time, Shankland had a golden opportunity to draw the hosts level but Gaston made an excellent stop from close range to deny the 28-goal man.
With the goal gaping, however, the Scotland international perhaps should’ve done better.
Despite throwing everything at it, Robbie Neilson’s men weren’t able to make the breakthrough, and made a rare slip up in their title procession.
Their lead at the top of the Championship now stands at 17 points, with Inverness in second having a game in hand.
Dundee United (4-4-2): Siegrist (GK); Smith, Connolly, Reynolds (C) (Mochrie 77), Robson; Pawlett, Powers, Butcher, Sporle; Sow (Glass 17) (Harkes 62), Shankland.
Subs not used: Deniz (GK), King, Neilson and Watson.
Arbroath (4-5-1): Gaston (GK); Thomson, Little, O’Brien (C), Hamilton; Gold (Craigen 71), Whatley, Swankie (Stewart 74), Virtanen, Hilson (Kader 86); Wighton.
Subs not used: Jamieson (GK), Linn, Donnelly and Murphy.
Referee: Alan Muir.