A fabulous winner from Dundee United substitute Scott Fraser with just five minutes to go lit up this dull William Hill Scottish Cup fifth round tie at Tannadice.
Fraser, who had come on for Ryan Dow, was played in by a terrific reverse pass from Blair Spittal and the midfielder sent his low drive into the far corner of the net.
It was a thing of beauty that looked out of place in an otherwise scrappy last-16 battle.
Fraser’s goal was enough to put the Tangerines into the quarter-final draw that will be made at Hampden on Monday night.
United, who signed former Inverness striker Edward Ofere pre-match, were meant to be badly-hit by a flu bug.
However, manager Mixu Paatelainen was still able to field the same 11 men who started against Kilmarnock in that remarkable 5-1 win last time out.
There was a place on the bench for loan signing Kyle Knoyle, while Florent Sinama-Pongolle was also one of the subs.
United’s transfer window target Steven Lawless was in the Partick side.
On six minutes, the home team came close when defender Coll Donaldson, upfield for a Spittal corner, headed over.
There was a scare for United three minutes later, though, when keeper Eiji Kawashima could only parry a Sean Welsh shot but the danger was cleared before Lawless could pounce.
Slack defending from the Jags on 18 minutes let John Rankin have a strike at goal but his shot was deflected past for a corner then Donaldson had an air shot when the ball came his way inside the box.
Thistle threatened on 28 minutes when Callum Booth crossed from the left and the ball just missed Welsh’s outstretched boot at the back post.
Six minutes before the break, United striker Simon Murray made space for himself but his low, angled shot was well saved by Thistle keeper Tomas Cerny.
The match had failed to catch fire but it nearly did on 67 minutes when United squandered a great chance.
Excellent work from Rankin saw him fire a low cross over from the left and, as it zipped across the face of the Thistle goal, you were left to wonder how Murray could fail to poke the ball over the line.
On 76 minutes, United sub Fraser tried his luck from the edge of the box but his strike was deflected for a corner.
The visitors broke clear on 84 minutes through sub David Amoo but the frontman was thwarted by Kawashima, who had raced out of his goal to put him off.
The winner came at the other end just a minute later and Fraser was the hero.
Spittal cut in from the left and, just as he looked likely to shoot, he played a glorious short pass to Fraser, who drove his shot low and beyond the reach of Jags keeper Cerny.
Dundee United: Kawashima, Dillon, Paton, Mckay (Durnan 88), Rankin, Dow (S. Fraser 74), Murray, Gunning, Spittal, Donaldson, Demel (Dixon 78). Subs not used: Zwick, Knoyle, Anier, Sinama-Pongolle.
Partick Thistle: Cerny, Miller, Seaborne, Welsh (G. Fraser 64), Booth, Osman, Bannigan, Doolan (Pogba 64), Lawless (Amoo 81), Frans, Lindsay. Subs not used: Scully, Elliott, Nesbitt, Edwards.