Dundee United had only themselves to blame on not leaving Glasgow with three points, passing up a barrowload of first-half chances, and then being stung by a second-half strike by Kris Doolan.
Victory would have seen United close to within two points of second-bottom Kilmarnock, who can breathe a sigh of relief at United’s ineptitude in front of goal.
Last night’s victory also kept alive the Jags’ hopes of a top-six finish.
Controversy was averted after nine minutes when Thistle’s Gary Fraser went down injured and United, instead of playing the ball out for the player to be treated, surged down the right with Henri Anier drilling the ball in low. Billy McKay laid the ball back to Ryan Dow, but his 10-yard effort was blocked by goalkeeper Tomas Cerny. Fraser never recovered and was replaced by Mathias Pogba, forcing Jags manager Alan Archibald into a tactical switch. United capitalised and bossed the midfield with Dow outstanding.
United were on the offensive again in 19 minutes when John Rankin flicked the ball back to Dow, but he volleyed over from 18 yards. Seconds later Dow forced Cerny into a save low to his right.
United should have gone in front in 23 minutes when Jags captain Abdul Osman was caught in possession. Guy Demel slid the ball back into the path of Dow, but he lashed the ball over from 10 yards.
On the half hour mark Thistle’s Dan Seaborne misplaced a clearance header straight to McKay, but with the goal gaping he scooped the ball over.
Chances fell thick and fast for Mixu Paatelainen’s side with Dow carving open the Thistle rearguard in 34 minutes. Rankin had space and time, but Cerny produced a wonderful save to turn the midfielder’s angled drive over.
One minute from the interval United finally had the ball in the net when Rankin cut the ball back to McKay, but it was ruled offside. Thistle raced to the other end and David Amoo cut in from the right, but his blistering close-range effort was deflected wide by the outstretched leg of Paul Dixon.
Thistle showed signs of a resurgence in the second half and in 54 minutes a Sean Welsgh corner from the left picked out Osman, but his 12-yard header looped over.
Three minutes later substitute Mustapha Dumbuya whipped over a cross from the right which Amoo headed back into the path of Callum Booth, who volleyed just wide.
United created an opening in 62 minutes when Dixon cut the ball back for Gavin Gunning, but his low drive was deflected past Cerny’s left post. And the visitors paid for scorning so many chances in 71 minutes when Dumbuya fired a low ball in from the right, Amoo stepped over and the lethal Kris Doolan drilled the ball low past goaklkeeper Eiji Kawashima from 12 yards.
United brought on Edward Ofere and Scott Fraser for Dixon and Dow, but it was Thistle who almost grabbed a second in 83 minutes when Sean Welsh pounced at the edge of the area, Kawashima getting down well to save.
Referee: A Dallas
PARTICK THISTLE: Cerny, Miller, Seaborne, Welsh, Booth, Osman, Amoo, Doolan (Edwards 80), Lawless, Frans (Dumbuya 48), Fraser (Pogba 12). Subs not used: Scully, Elliott, Nesbitt, Nisbet. Booked: Frans 2, Booth 85.
DUNDEE UNITED: Kawashima, Dixon (Ofere 79), Morris, Paton, McKay, Rankin, Knoyle, Dow (Fraser 79), Gunning, Anier, Demel (Spittal 66). Subs not used: Szromnik, Dillon, Murray, Durnan. Booked: Fraser 90.