Johnny Russell's second-half penalty gave Dundee United their first Scottish Premier League win since August as St Mirren suffered a third straight loss.
Lee Mair came closest to a first-half opener, the Buddies defender glancing a header wide.
United's Gavin Gunning nodded against the crossbar after the break.
And the visitors took the lead after Steven Thompson had been penalised for handball, Russell powering the ball home from 12 yards.
St Mirren replace United as the league's second-bottom side, with 10th-place United also on 12 points but boasting a better goal difference.
The first real chance came for the Tangerines with goalkeeper Craig Samson spilling Mark Millar's 19-yard shot before recovering the ball.
Mair glanced a header just wide of the United goal after meeting Dougie Imrie's corner and St Mirren captain Jim Goodwin was also off-target with a controlled 35-yard strike.
United had been restricted to long-range efforts and manager Peter Houston cut a frustrated figure in the visiting technical area.
Houston did have a potential ace up his sleeve in the form of new signing Rudi Skacel, scorer of 10 goals in six games against St Mirren for Hearts over the past two seasons, but the Czech midfielder's lack of match practice meant he would not appear until after the break.
St Mirren dominated possession but struggled to break the Tannadice side down and there was a sense a relief when the whistle sounded for half-time, with both sets of fans hoping for a better second half.
And Gunning almost broke the deadlock when he rose to head Willo Flood's free-kick onto the bar on 50 minutes.
Skacel and Richie Ryan came on in place of Millar and Michael Gardyne but United nearly found themselves behind when Lewis Guy turned the ball towards goal only for Radoslaw Cierzniak to smother the ball on the line.
Referee Euan Norris pointed to the spot after Thompson's outstretched limb made contact with Flood's corner and Samson was unable to prevent Russell's low strike finding the net.
St Mirren tried to respond and Goodwin's volley dipped into the arms of Cierzniak.
United held firm, albeit with some frantic defending as St Mirren shelled balls into the box.
Skacel almost got in for a scoring chance on the break late on but one goal proved to be enough for Houston's men.
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Live Text Commentary
Full Time The referee ends the match.90:00 +2:33
The referee blows for offside against Ryan Dow. Craig Samson takes the free kick.90:00 +1:36
Sam Parkin challenges Keith Watson unfairly and gives away a free kick. Free kick taken by Jon Daly.90:00 +0:58
Free kick awarded for an unfair challenge on Steven Thompson by Jon Daly. Free kick crossed left-footed by Graham Carey from left wing, clearance by Sean Dillon.87:28
Foul by Jim Goodwin on Richie Ryan, free kick awarded. Willo Flood takes the direct free kick.86:51
Effort from the edge of the area by Jim Goodwin goes wide of the right-hand upright.84:47 Substitution
Substitution (St Mirren) makes a substitution, with Thomas Reilly coming on for Dougie Imrie.83:58
Unfair challenge on Sean Dillon by Sam Parkin results in a free kick. Sean Dillon restarts play with the free kick.82:01
Free kick awarded for an unfair challenge on Rudi Skacel by Jim Goodwin. Keith Watson takes the direct free kick.79:53 Substitution
Substitution Ryan Dow joins the action as a substitute, replacing Stuart Armstrong.79:53 Substitution
Substitution Gary Teale on for Jon Robertson.77:38
Free kick awarded for a foul by Willo Flood on Dougie Imrie. Free kick taken by Paul Dummett.77:09
Shot from 18 yards by Jim Goodwin. Save by Radoslaw Cierzniak.76:12
Marc McAusland fouled by Johnny Russell, the ref awards a free kick. Marc McAusland takes the direct free kick.75:01
Free kick awarded for an unfair challenge on Rudi Skacel by Paul Dummett. Radoslaw Cierzniak takes the free kick.74:33
Jim Goodwin fouled by Rudi Skacel, the ref awards a free kick. Marc McAusland restarts play with the free kick.73:33
Inswinging corner taken by Jim Goodwin, Gavin Gunning makes a clearance.73:07
The assistant referee signals for offside against Rudi Skacel. Lee Mair takes the indirect free kick.71:45 Substitution
Substitution Sam Parkin comes on in place of Lewis Guy.70:05
Corner taken right-footed by Willo Flood from the right by-line, Lee Mair manages to make a clearance.
Goal! - Johnny Russell - St Mirren 0 - 1 Dundee U Penalty taken left-footed by Johnny Russell and scored. St Mirren 0-1 Dundee Utd.68:13 Booking
Booking The referee cautions Steven Thompson for unsporting behaviour.67:16
Inswinging corner taken right-footed by Willo Flood from the left by-line. Steven Thompson is adjudged to have handled the ball.64:05 Substitution
Substitution Rudi Skacel joins the action as a substitute, replacing Michael Gardyne.64:05 Substitution
Substitution (Dundee Utd) makes a substitution, with Richie Ryan coming on for Mark Millar.64:05
Direct free kick taken by Marc McAusland.64:05 Booking
Booking Mark Millar is shown a yellow card for unsporting behaviour.63:52
Foul by Mark Millar on Dougie Imrie, free kick awarded.56:54
Inswinging corner taken right-footed by Jim Goodwin, Gavin Gunning manages to make a clearance.55:58
Free kick awarded for an unfair challenge on Willo Flood by Jim Goodwin. Direct free kick taken by Willo Flood.53:24
Dougie Imrie concedes a free kick for a foul on Michael Gardyne. Willo Flood restarts play with the free kick.50:24
Gavin Gunning takes a shot.49:49
Foul by Jim Goodwin on Mark Millar, free kick awarded. Direct free kick taken by Willo Flood.48:27
Inswinging corner taken by Jim Goodwin, Gavin Gunning manages to make a clearance.46:07
Willo Flood concedes a free kick for a foul on Dougie Imrie. Jim Goodwin takes the direct free kick.45:43
Dougie Imrie gives away a free kick for an unfair challenge on Keith Watson. Radoslaw Cierzniak takes the free kick.45:01
The referee gets the second half started.45:00 +0:07 Half time
Half Time The players leave the pitch at half time.41:23
Free kick awarded for a foul by Marc McAusland on Johnny Russell. John Rankin takes the direct free kick.32:22
Jon Daly challenges Steven Thompson unfairly and gives away a free kick. Dougie Imrie takes the direct free kick.31:33
Inswinging corner taken by Jim Goodwin from the left by-line, clearance by John Rankin.29:55
Free kick awarded for a foul by Mark Millar on Jon Robertson. Graham Carey shoots direct from the free kick.23:05
Effort on goal by Jim Goodwin from long range goes over the bar.19:50
Willo Flood concedes a free kick for a foul on Jim Goodwin. The free kick is swung in left-footed by Graham Carey, Radoslaw Cierzniak makes a save.16:53
Dougie Imrie fouled by Keith Watson, the ref awards a free kick. Free kick crossed by Jim Goodwin, clearance by Radoslaw Cierzniak.15:22
Free kick awarded for a foul by Stuart Armstrong on David van Zanten. Jim Goodwin takes the direct free kick.14:25
Inswinging corner taken left-footed by Dougie Imrie, Lee Mair produces a header from close range which goes wide of the left-hand post.13:30
Shot by Stuart Armstrong from outside the box goes high over the target.12:28
Inswinging corner taken by Jim Goodwin, Gavin Gunning makes a clearance.11:10
Mark Millar takes a shot. Craig Samson makes a comfortable save.4:21
Jon Daly gives away a free kick for an unfair challenge on Lewis Guy. Graham Carey restarts play with the free kick.3:21
Unfair challenge on Mark Millar by Lee Mair results in a free kick. Free kick taken by Willo Flood.2:09
The referee gives a free kick against Lewis Guy for handball. Direct free kick taken by Willo Flood.1:34
Free kick awarded for a foul by Jim Goodwin on John Rankin. Sean Dillon takes the free kick.0:00
The ref blows the whistle to start the match.
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