A Filip Kiss brace and a debut goal from new signing Yoann Arquin saw Ross County pick up another victory to improve their prospects of avoiding relegation from the Scottish Premiership.
Kiss opened the scoring four minutes from the break and wrapped up the win with a stunning 30-yard drive, after Arquin had chested in a second goal midway through the second half.
The 3-0 victory moved the Staggies above Partick - and importantly out of the relegation play-off place.
The visitors had the first shot on target in the third minute when Farid El Alagui took advantage of a slip from Kiss and let fly at goal. County keeper Michael Fraser managed to palm away the shot and John Rankin fired the rebound across the face of goal and behind.
At the other end an accurate pass from Ben Gordon almost put Jordan Slew in on goal but Calum Butcher got in a timely tackle to avert the danger.
County won a corner just outside the 18-yard box in the 10th minute but Graham Carey's effort was well held by Radoslaw Cierzniak.
But United looked dangerous on the break and when Paul Paton slipped the ball through to Keith Watson on the right, his cross found El Alagui in the box. However, the on-loan Brentford player failed to test Fraser from 10 yards.
County had another set-piece chance in the 14th minute but this time Richard Brittain brought a save from Cierzniak.
The home side threatened again three minutes later when Slew drove from the halfway line before he was upended by Butcher just outside the area.
County came closer in the 22nd minute when Carey chipped the ball in for Slew, who forced a fine point blank save from Cierzniak.
The home side broke the deadlock in the 42nd minute when Brittain returned the ball to Carey following a corner on the left and his first-time cross was headed high into the net by Kiss on the six-yard line.
County had the ball in the net in first half stoppage time when Brian McLean side-footed home a Carey free-kick - but the flag went up for offside.
United started the second half on the front foot and Gary MacKay-Steven flashed in an angled shot which was turned away by Fraser.
County replied at the other end when Slew cut the ball back for Carey, whose low drive was deflected behind for a corner.
Then Michael Tidser blasted a shot from 25 yards which flashed past Cierzniak's left hand post as County went all out for a second goal.
United made an early substitution with Nadir Ciftci coming on for Chris Erskine, who had been booked just before.
The new arrival was soon in the action as he fired a shot over the crossbar from the edge of the area.
However, County doubled their lead in the 69th minute when Slew cut in from the left and his goalbound shot was chested over the line by Arquin.
It was all over as a contest four minutes later when Kiss found the top corner of the net with a sensational 30-yard drive.